Instruction:
Can you tell what is the following Python 3 function doing
def structured_traceback(self, etype, evalue, etb, tb_offset=None,
                             context=5):
        """Return a nice text document describing the traceback."""

        tb_offset = self.tb_offset if tb_offset is None else tb_offset

        # some locals
        try:
            etype = etype.__name__
        except AttributeError:
            pass
        Colors        = self.Colors   # just a shorthand + quicker name lookup
        ColorsNormal  = Colors.Normal  # used a lot
        col_scheme    = self.color_scheme_table.active_scheme_name
        indent        = ' '*INDENT_SIZE
        em_normal     = '%s\n%s%s' % (Colors.valEm, indent,ColorsNormal)
        undefined     = '%sundefined%s' % (Colors.em, ColorsNormal)
        exc = '%s%s%s' % (Colors.excName,etype,ColorsNormal)

        # some internal-use functions
        def text_repr(value):
            """Hopefully pretty robust repr equivalent."""
            # this is pretty horrible but should always return *something*
            try:
                return pydoc.text.repr(value)
            except KeyboardInterrupt:
                raise
            except:
                try:
                    return repr(value)
                except KeyboardInterrupt:
                    raise
                except:
                    try:
                        # all still in an except block so we catch
                        # getattr raising
                        name = getattr(value, '__name__', None)
                        if name:
                            # ick, recursion
                            return text_repr(name)
                        klass = getattr(value, '__class__', None)
                        if klass:
                            return '%s instance' % text_repr(klass)
                    except KeyboardInterrupt:
                        raise
                    except:
                        return 'UNRECOVERABLE REPR FAILURE'
        def eqrepr(value, repr=text_repr): return '=%s' % repr(value)
        def nullrepr(value, repr=text_repr): return ''

        # meat of the code begins
        try:
            etype = etype.__name__
        except AttributeError:
            pass

        if self.long_header:
            # Header with the exception type, python version, and date
            pyver = 'Python ' + sys.version.split()[0] + ': ' + sys.executable
            date = time.ctime(time.time())

            head = '%s%s%s\n%s%s%s\n%s' % (Colors.topline, '-'*75, ColorsNormal,
                                           exc, ' '*(75-len(str(etype))-len(pyver)),
                                           pyver, date.rjust(75) )
            head += "\nA problem occured executing Python code.  Here is the sequence of function"\
                    "\ncalls leading up to the error, with the most recent (innermost) call last."
        else:
            # Simplified header
            head = '%s%s%s\n%s%s' % (Colors.topline, '-'*75, ColorsNormal,exc,
                                     'Traceback (most recent call last)'.\
                                                  rjust(75 - len(str(etype)) ) )
        frames = []
        # Flush cache before calling inspect.  This helps alleviate some of the
        # problems with python 2.3's inspect.py.
        ##self.check_cache()
        # Drop topmost frames if requested
        try:
            # Try the default getinnerframes and Alex's: Alex's fixes some
            # problems, but it generates empty tracebacks for console errors
            # (5 blanks lines) where none should be returned.
            #records = inspect.getinnerframes(etb, context)[tb_offset:]
            #print 'python records:', records # dbg
            records = _fixed_getinnerframes(etb, context, tb_offset)
            #print 'alex   records:', records # dbg
        except:

            # FIXME: I've been getting many crash reports from python 2.3
            # users, traceable to inspect.py.  If I can find a small test-case
            # to reproduce this, I should either write a better workaround or
            # file a bug report against inspect (if that's the real problem).
            # So far, I haven't been able to find an isolated example to
            # reproduce the problem.
            inspect_error()
            traceback.print_exc(file=self.ostream)
            info('\nUnfortunately, your original traceback can not be constructed.\n')
            return ''

        # build some color string templates outside these nested loops
        tpl_link       = '%s%%s%s' % (Colors.filenameEm,ColorsNormal)
        tpl_call       = 'in %s%%s%s%%s%s' % (Colors.vName, Colors.valEm,
                                              ColorsNormal)
        tpl_call_fail  = 'in %s%%s%s(***failed resolving arguments***)%s' % \
                         (Colors.vName, Colors.valEm, ColorsNormal)
        tpl_local_var  = '%s%%s%s' % (Colors.vName, ColorsNormal)
        tpl_global_var = '%sglobal%s %s%%s%s' % (Colors.em, ColorsNormal,
                                                 Colors.vName, ColorsNormal)
        tpl_name_val   = '%%s %s= %%s%s' % (Colors.valEm, ColorsNormal)
        tpl_line       = '%s%%s%s %%s' % (Colors.lineno, ColorsNormal)
        tpl_line_em    = '%s%%s%s %%s%s' % (Colors.linenoEm,Colors.line,
                                            ColorsNormal)

        # now, loop over all records printing context and info
        abspath = os.path.abspath
        for frame, file, lnum, func, lines, index in records:
            #print '*** record:',file,lnum,func,lines,index  # dbg

            if not file:
                file = '?'
            elif not(file.startswith("<") and file.endswith(">")):
                # Guess that filenames like <string> aren't real filenames, so
                # don't call abspath on them.
                try:
                    file = abspath(file)
                except OSError:
                    # Not sure if this can still happen: abspath now works with
                    # file names like <string>
                    pass

            link = tpl_link % file
            args, varargs, varkw, locals = inspect.getargvalues(frame)

            if func == '?':
                call = ''
            else:
                # Decide whether to include variable details or not
                var_repr = self.include_vars and eqrepr or nullrepr
                try:
                    call = tpl_call % (func,inspect.formatargvalues(args,
                                                varargs, varkw,
                                                locals,formatvalue=var_repr))
                except KeyError:
                    # This happens in situations like errors inside generator
                    # expressions, where local variables are listed in the
                    # line, but can't be extracted from the frame.  I'm not
                    # 100% sure this isn't actually a bug in inspect itself,
                    # but since there's no info for us to compute with, the
                    # best we can do is report the failure and move on.  Here
                    # we must *not* call any traceback construction again,
                    # because that would mess up use of %debug later on.  So we
                    # simply report the failure and move on.  The only
                    # limitation will be that this frame won't have locals
                    # listed in the call signature.  Quite subtle problem...
                    # I can't think of a good way to validate this in a unit
                    # test, but running a script consisting of:
                    #  dict( (k,v.strip()) for (k,v) in range(10) )
                    # will illustrate the error, if this exception catch is
                    # disabled.
                    call = tpl_call_fail % func

            # Don't attempt to tokenize binary files.
            if file.endswith(('.so', '.pyd', '.dll')):
                frames.append('%s %s\n' % (link,call))
                continue
            elif file.endswith(('.pyc','.pyo')):
                # Look up the corresponding source file.
                file = pyfile.source_from_cache(file)

            def linereader(file=file, lnum=[lnum], getline=linecache.getline):
                line = getline(file, lnum[0])
                lnum[0] += 1
                return line

            # Build the list of names on this line of code where the exception
            # occurred.
            try:
                names = []
                name_cont = False

                for token_type, token, start, end, line in generate_tokens(linereader):
                    # build composite names
                    if token_type == tokenize.NAME and token not in keyword.kwlist:
                        if name_cont:
                            # Continuation of a dotted name
                            try:
                                names[-1].append(token)
                            except IndexError:
                                names.append([token])
                            name_cont = False
                        else:
                            # Regular new names.  We append everything, the caller
                            # will be responsible for pruning the list later.  It's
                            # very tricky to try to prune as we go, b/c composite
                            # names can fool us.  The pruning at the end is easy
                            # to do (or the caller can print a list with repeated
                            # names if so desired.
                            names.append([token])
                    elif token == '.':
                        name_cont = True
                    elif token_type == tokenize.NEWLINE:
                        break

            except (IndexError, UnicodeDecodeError):
                # signals exit of tokenizer
                pass
            except tokenize.TokenError,msg:
                _m = ("An unexpected error occurred while tokenizing input\n"
                      "The following traceback may be corrupted or invalid\n"
                      "The error message is: %s\n" % msg)
                error(_m)

            # Join composite names (e.g. "dict.fromkeys")
            names = ['.'.join(n) for n in names]
            # prune names list of duplicates, but keep the right order
            unique_names = uniq_stable(names)

            # Start loop over vars
            lvals = []
            if self.include_vars:
                for name_full in unique_names:
                    name_base = name_full.split('.',1)[0]
                    if name_base in frame.f_code.co_varnames:
                        if locals.has_key(name_base):
                            try:
                                value = repr(eval(name_full,locals))
                            except:
                                value = undefined
                        else:
                            value = undefined
                        name = tpl_local_var % name_full
                    else:
                        if frame.f_globals.has_key(name_base):
                            try:
                                value = repr(eval(name_full,frame.f_globals))
                            except:
                                value = undefined
                        else:
                            value = undefined
                        name = tpl_global_var % name_full
                    lvals.append(tpl_name_val % (name,value))
            if lvals:
                lvals = '%s%s' % (indent,em_normal.join(lvals))
            else:
                lvals = ''

            level = '%s %s\n' % (link,call)

            if index is None:
                frames.append(level)
            else:
                frames.append('%s%s' % (level,''.join(
                    _format_traceback_lines(lnum,index,lines,Colors,lvals,
                                            col_scheme))))

        # Get (safely) a string form of the exception info
        try:
            etype_str,evalue_str = map(str,(etype,evalue))
        except:
            # User exception is improperly defined.
            etype,evalue = str,sys.exc_info()[:2]
            etype_str,evalue_str = map(str,(etype,evalue))
        # ... and format it
        exception = ['%s%s%s: %s' % (Colors.excName, etype_str,
                                     ColorsNormal, evalue_str)]
        if (not py3compat.PY3) and type(evalue) is types.InstanceType:
            try:
                names = [w for w in dir(evalue) if isinstance(w, basestring)]
            except:
                # Every now and then, an object with funny inernals blows up
                # when dir() is called on it.  We do the best we can to report
                # the problem and continue
                _m = '%sException reporting error (object with broken dir())%s:'
                exception.append(_m % (Colors.excName,ColorsNormal))
                etype_str,evalue_str = map(str,sys.exc_info()[:2])
                exception.append('%s%s%s: %s' % (Colors.excName,etype_str,
                                     ColorsNormal, evalue_str))
                names = []
            for name in names:
                value = text_repr(getattr(evalue, name))
                exception.append('\n%s%s = %s' % (indent, name, value))

        # vds: >>
        if records:
             filepath, lnum = records[-1][1:3]
             #print "file:", str(file), "linenb", str(lnum) # dbg
             filepath = os.path.abspath(filepath)
             ipinst = ipapi.get()
             if ipinst is not None:
                 ipinst.hooks.synchronize_with_editor(filepath, lnum, 0)
        # vds: <<

        # return all our info assembled as a single string
        # return '%s\n\n%s\n%s' % (head,'\n'.join(frames),''.join(exception[0]) )
        return [head] + frames + [''.join(exception[0])]

Response: Return a nice text document describing the traceback.


Instruction:
Can you generate a brief explanation for the following Python 3 code
def debugger(self,force=False):

        if force or self.call_pdb:
            if self.pdb is None:
                self.pdb = debugger.Pdb(
                    self.color_scheme_table.active_scheme_name)
            # the system displayhook may have changed, restore the original
            # for pdb
            display_trap = DisplayTrap(hook=sys.__displayhook__)
            with display_trap:
                self.pdb.reset()
                # Find the right frame so we don't pop up inside ipython itself
                if hasattr(self,'tb') and self.tb is not None:
                    etb = self.tb
                else:
                    etb = self.tb = sys.last_traceback
                while self.tb is not None and self.tb.tb_next is not None:
                    self.tb = self.tb.tb_next
                if etb and etb.tb_next:
                    etb = etb.tb_next
                self.pdb.botframe = etb.tb_frame
                self.pdb.interaction(self.tb.tb_frame, self.tb)

        if hasattr(self,'tb'):
            del self.tb

Response: Call up the debugger if desired.


Instruction:
Implement a function in Python 3 to
switch to the desired mode.

Response:
def set_mode(self,mode=None):
        """Switch to the desired mode.

        If mode is not specified, cycles through the available modes."""

        if not mode:
            new_idx = ( self.valid_modes.index(self.mode) + 1 ) % \
                      len(self.valid_modes)
            self.mode = self.valid_modes[new_idx]
        elif mode not in self.valid_modes:
            raise ValueError, 'Unrecognized mode in FormattedTB: <'+mode+'>\n'\
                  'Valid modes: '+str(self.valid_modes)
        else:
            self.mode = mode
        # include variable details only in 'Verbose' mode
        self.include_vars = (self.mode == self.valid_modes[2])
        # Set the join character for generating text tracebacks
        self.tb_join_char = self._join_chars[self.mode]


Instruction:
Can you tell what is the following Python 3 function doing
def group_required(group,
                   login_url=None,
                   redirect_field_name=REDIRECT_FIELD_NAME,
                   skip_superuser=True):
    """
    View decorator for requiring a user group.
    """
    def decorator(view_func):
        @login_required(redirect_field_name=redirect_field_name,
                        login_url=login_url)
        def _wrapped_view(request, *args, **kwargs):

            if not (request.user.is_superuser and skip_superuser):
                if request.user.groups.filter(name=group).count() == 0:
                    raise PermissionDenied

            return view_func(request, *args, **kwargs)
        return _wrapped_view

    return decorator

Response: Decorator for making views that require a user group.


Instruction:
Write a Python 3 script for
getting the parent of the current module.

Response:
def get_parent(globals, level):
    """
    parent, name = get_parent(globals, level)

    Return the package that an import is being performed in.  If globals comes
    from the module foo.bar.bat (not itself a package), this returns the
    sys.modules entry for foo.bar.  If globals is from a package's __init__.py,
    the package's entry in sys.modules is returned.

    If globals doesn't come from a package or a module in a package, or a
    corresponding entry is not found in sys.modules, None is returned.
    """
    orig_level = level

    if not level or not isinstance(globals, dict):
        return None, ''

    pkgname = globals.get('__package__', None)

    if pkgname is not None:
        # __package__ is set, so use it
        if not hasattr(pkgname, 'rindex'):
            raise ValueError('__package__ set to non-string')
        if len(pkgname) == 0:
            if level > 0:
                raise ValueError('Attempted relative import in non-package')
            return None, ''
        name = pkgname
    else:
        # __package__ not set, so figure it out and set it
        if '__name__' not in globals:
            return None, ''
        modname = globals['__name__']

        if '__path__' in globals:
            # __path__ is set, so modname is already the package name
            globals['__package__'] = name = modname
        else:
            # Normal module, so work out the package name if any
            lastdot = modname.rfind('.')
            if lastdot < 0 and level > 0:
                raise ValueError("Attempted relative import in non-package")
            if lastdot < 0:
                globals['__package__'] = None
                return None, ''
            globals['__package__'] = name = modname[:lastdot]

    dot = len(name)
    for x in xrange(level, 1, -1):
        try:
            dot = name.rindex('.', 0, dot)
        except ValueError:
            raise ValueError("attempted relative import beyond top-level "
                             "package")
    name = name[:dot]

    try:
        parent = sys.modules[name]
    except:
        if orig_level < 1:
            warn("Parent module '%.200s' not found while handling absolute "
                 "import" % name)
            parent = None
        else:
            raise SystemError("Parent module '%.200s' not loaded, cannot "
                              "perform relative import" % name)

    # We expect, but can't guarantee, if parent != None, that:
    # - parent.__name__ == name
    # - parent.__dict__ is globals
    # If this is violated...  Who cares?
    return parent, name


Instruction:
Can you create a Python 3 function that
loads next module in the sequence of modules.

Response:
def load_next(mod, altmod, name, buf):
    """
    mod, name, buf = load_next(mod, altmod, name, buf)

    altmod is either None or same as mod
    """

    if len(name) == 0:
        # completely empty module name should only happen in
        # 'from . import' (or '__import__("")')
        return mod, None, buf

    dot = name.find('.')
    if dot == 0:
        raise ValueError('Empty module name')

    if dot < 0:
        subname = name
        next = None
    else:
        subname = name[:dot]
        next = name[dot+1:]

    if buf != '':
        buf += '.'
    buf += subname

    result = import_submodule(mod, subname, buf)
    if result is None and mod != altmod:
        result = import_submodule(altmod, subname, subname)
        if result is not None:
            buf = subname

    if result is None:
        raise ImportError("No module named %.200s" % name)

    return result, next, buf


Instruction:
Can you generate a brief explanation for the following Python 3 code
def import_submodule(mod, subname, fullname):
    # Require:
    # if mod == None: subname == fullname
    # else: mod.__name__ + "." + subname == fullname

    global found_now
    if fullname in found_now and fullname in sys.modules:
        m = sys.modules[fullname]
    else:
        print 'Reloading', fullname
        found_now[fullname] = 1
        oldm = sys.modules.get(fullname, None)

        if mod is None:
            path = None
        elif hasattr(mod, '__path__'):
            path = mod.__path__
        else:
            return None

        try:
            # This appears to be necessary on Python 3, because imp.find_module()
            # tries to import standard libraries (like io) itself, and we don't
            # want them to be processed by our deep_import_hook.
            with replace_import_hook(original_import):
                fp, filename, stuff = imp.find_module(subname, path)
        except ImportError:
            return None

        try:
            m = imp.load_module(fullname, fp, filename, stuff)
        except:
            # load_module probably removed name from modules because of
            # the error.  Put back the original module object.
            if oldm:
                sys.modules[fullname] = oldm
            raise
        finally:
            if fp: fp.close()

        add_submodule(mod, m, fullname, subname)

    return m

Response: Import a module and return the module object.


Instruction:
Implement a function in Python 3 to
add a submodule to the module

Response:
def add_submodule(mod, submod, fullname, subname):
    """mod.{subname} = submod"""
    if mod is None:
        return #Nothing to do here.

    if submod is None:
        submod = sys.modules[fullname]

    setattr(mod, subname, submod)

    return


Instruction:
Can you generate a brief explanation for the following Python 3 code
def ensure_fromlist(mod, fromlist, buf, recursive):
    if not hasattr(mod, '__path__'):
        return
    for item in fromlist:
        if not hasattr(item, 'rindex'):
            raise TypeError("Item in ``from list'' not a string")
        if item == '*':
            if recursive:
                continue # avoid endless recursion
            try:
                all = mod.__all__
            except AttributeError:
                pass
            else:
                ret = ensure_fromlist(mod, all, buf, 1)
                if not ret:
                    return 0
        elif not hasattr(mod, item):
            import_submodule(mod, item, buf + '.' + item)

Response: Handle from module import a b c imports.


Instruction:
Here you have a function in Python 3, explain what it does
def code_name(code, number=0):
    hash_digest = hashlib.md5(code.encode("utf-8")).hexdigest()
    # Include the number and 12 characters of the hash in the name.  It's
    # pretty much impossible that in a single session we'll have collisions
    # even with truncated hashes, and the full one makes tracebacks too long
    return '<ipython-input-{0}-{1}>'.format(number, hash_digest[:12])

Response: Compute a unique name for a code.


Instruction:
How would you code a function in Python 3 to
parse code to an AST with the current compiler flags active.

Response:
def ast_parse(self, source, filename='<unknown>', symbol='exec'):
        """Parse code to an AST with the current compiler flags active.

        Arguments are exactly the same as ast.parse (in the standard library),
        and are passed to the built-in compile function."""
        return compile(source, filename, symbol, self.flags | PyCF_ONLY_AST, 1)


Instruction:
Create a Python 3 function for
making a name for a block of code, and cache the code. Parameters ---------- code : str The Python source code to cache. number : int A number which forms part of the code's name. Used for the execution counter. Returns ------- The name of the cached code (as a string). Pass this as the filename argument to compilation, so that tracebacks are correctly hooked up.

Response:
def cache(self, code, number=0):
        """Make a name for a block of code, and cache the code.

        Parameters
        ----------
        code : str
          The Python source code to cache.
        number : int
          A number which forms part of the code's name. Used for the execution
          counter.

        Returns
        -------
        The name of the cached code (as a string). Pass this as the filename
        argument to compilation, so that tracebacks are correctly hooked up.
        """
        name = code_name(code, number)
        entry = (len(code), time.time(),
                 [line+'\n' for line in code.splitlines()], name)
        linecache.cache[name] = entry
        linecache._ipython_cache[name] = entry
        return name


Instruction:
How would you code a function in Python 3 to
call the orignal checkcache as intended and update the cache with our data.

Response:
def check_cache(self, *args):
        """Call linecache.checkcache() safely protecting our cached values.
        """
        # First call the orignal checkcache as intended
        linecache._checkcache_ori(*args)
        # Then, update back the cache with our data, so that tracebacks related
        # to our compiled codes can be produced.
        linecache.cache.update(linecache._ipython_cache)


Instruction:
How would you code a function in Python 3 to
add a line of source to the code.

Response:
def add_line(self, line):
        """Add a line of source to the code.

        Don't include indentations or newlines.

        """
        self.code.append(" " * self.indent_amount)
        self.code.append(line)
        self.code.append("\n")


Instruction:
Create a Python 3 function to
add a section a sub - CodeBuilder.

Response:
def add_section(self):
        """Add a section, a sub-CodeBuilder."""
        sect = CodeBuilder(self.indent_amount)
        self.code.append(sect)
        return sect


Instruction:
Given the following Python 3 function, write the documentation
def get_function(self, fn_name):
        assert self.indent_amount == 0
        g = {}
        code_text = str(self)
        exec(code_text, g)
        return g[fn_name]

Response: Compile the code and return the function fn_name.


Instruction:
Can you write a function in Python 3 where it
generates a Python expression for expr.

Response:
def expr_code(self, expr):
        """Generate a Python expression for `expr`."""
        if "|" in expr:
            pipes = expr.split("|")
            code = self.expr_code(pipes[0])
            for func in pipes[1:]:
                self.all_vars.add(func)
                code = "c_%s(%s)" % (func, code)
        elif "." in expr:
            dots = expr.split(".")
            code = self.expr_code(dots[0])
            args = [repr(d) for d in dots[1:]]
            code = "dot(%s, %s)" % (code, ", ".join(args))
        else:
            self.all_vars.add(expr)
            code = "c_%s" % expr
        return code


Instruction:
Implement a Python 3 function for
rendering this template by applying it to context.

Response:
def render(self, context=None):
        """Render this template by applying it to `context`.

        `context` is a dictionary of values to use in this rendering.

        """
        # Make the complete context we'll use.
        ctx = dict(self.context)
        if context:
            ctx.update(context)
        return self.render_function(ctx, self.do_dots)


Instruction:
How would you explain what the following Python 3 function does
def do_dots(self, value, *dots):
        for dot in dots:
            try:
                value = getattr(value, dot)
            except AttributeError:
                value = value[dot]
            if hasattr(value, '__call__'):
                value = value()
        return value

Response: Evaluate dotted expressions at runtime.


Instruction:
How would you explain what the following Python 3 function does
def render_template(tpl, context):
    '''
    A shortcut function to render a partial template with context and return
    the output.
    '''

    templates = [tpl] if type(tpl) != list else tpl
    tpl_instance = None

    for tpl in templates:
        try:
            tpl_instance = template.loader.get_template(tpl)
            break
        except template.TemplateDoesNotExist:
            pass

    if not tpl_instance:
        raise Exception('Template does not exist: ' + templates[-1])

    return tpl_instance.render(template.Context(context))

Response:
A shortcut function to render a partial template with context and return
    the output.


Instruction:
Create a Python 3 function to
return a format data dict for an object.

Response:
def format_display_data(obj, include=None, exclude=None):
    """Return a format data dict for an object.

    By default all format types will be computed.

    The following MIME types are currently implemented:

    * text/plain
    * text/html
    * text/latex
    * application/json
    * application/javascript
    * image/png
    * image/jpeg
    * image/svg+xml

    Parameters
    ----------
    obj : object
        The Python object whose format data will be computed.

    Returns
    -------
    format_dict : dict
        A dictionary of key/value pairs, one or each format that was
        generated for the object. The keys are the format types, which
        will usually be MIME type strings and the values and JSON'able
        data structure containing the raw data for the representation in
        that format.
    include : list or tuple, optional
        A list of format type strings (MIME types) to include in the
        format data dict. If this is set *only* the format types included
        in this list will be computed.
    exclude : list or tuple, optional
        A list of format type string (MIME types) to exclue in the format
        data dict. If this is set all format types will be computed,
        except for those included in this argument.
    """
    from IPython.core.interactiveshell import InteractiveShell

    InteractiveShell.instance().display_formatter.format(
        obj,
        include,
        exclude
    )


Instruction:
Explain what the following Python 3 code does
def _formatters_default(self):
        formatter_classes = [
            PlainTextFormatter,
            HTMLFormatter,
            SVGFormatter,
            PNGFormatter,
            JPEGFormatter,
            LatexFormatter,
            JSONFormatter,
            JavascriptFormatter
        ]
        d = {}
        for cls in formatter_classes:
            f = cls(config=self.config)
            d[f.format_type] = f
        return d

Response: Activate the default formatters.


Instruction:
How would you explain what the following Python 3 function does
def format(self, obj, include=None, exclude=None):
        format_dict = {}

        # If plain text only is active
        if self.plain_text_only:
            formatter = self.formatters['text/plain']
            try:
                data = formatter(obj)
            except:
                # FIXME: log the exception
                raise
            if data is not None:
                format_dict['text/plain'] = data
            return format_dict

        for format_type, formatter in self.formatters.items():
            if include is not None:
                if format_type not in include:
                    continue
            if exclude is not None:
                if format_type in exclude:
                    continue
            try:
                data = formatter(obj)
            except:
                # FIXME: log the exception
                raise
            if data is not None:
                format_dict[format_type] = data
        return format_dict

Response: Return a format data dict for an object.


Instruction:
Write a Python 3 script for
adding a format function for a given type.

Response:
def for_type(self, typ, func):
        """Add a format function for a given type.

        Parameters
        -----------
        typ : class
            The class of the object that will be formatted using `func`.
        func : callable
            The callable that will be called to compute the format data. The
            call signature of this function is simple, it must take the
            object to be formatted and return the raw data for the given
            format. Subclasses may use a different call signature for the
            `func` argument.
        """
        oldfunc = self.type_printers.get(typ, None)
        if func is not None:
            # To support easy restoration of old printers, we need to ignore
            # Nones.
            self.type_printers[typ] = func
        return oldfunc


Instruction:
Write a Python 3 script for
adding a format function for a type specified by the full dotted name of the module and the name of the object.

Response:
def for_type_by_name(self, type_module, type_name, func):
        """Add a format function for a type specified by the full dotted
        module and name of the type, rather than the type of the object.

        Parameters
        ----------
        type_module : str
            The full dotted name of the module the type is defined in, like
            ``numpy``.
        type_name : str
            The name of the type (the class name), like ``dtype``
        func : callable
            The callable that will be called to compute the format data. The
            call signature of this function is simple, it must take the
            object to be formatted and return the raw data for the given
            format. Subclasses may use a different call signature for the
            `func` argument.
        """
        key = (type_module, type_name)
        oldfunc = self.deferred_printers.get(key, None)
        if func is not None:
            # To support easy restoration of old printers, we need to ignore
            # Nones.
            self.deferred_printers[key] = func
        return oldfunc


Instruction:
Given the following Python 3 function, write the documentation
def _in_deferred_types(self, cls):
        mod = getattr(cls, '__module__', None)
        name = getattr(cls, '__name__', None)
        key = (mod, name)
        printer = None
        if key in self.deferred_printers:
            # Move the printer over to the regular registry.
            printer = self.deferred_printers.pop(key)
            self.type_printers[cls] = printer
        return printer

Response: Check if the given class is specified in the deferred type registry. If it does return the printer that is registered under the given class. If it does return None.


Instruction:
Given the following Python 3 function, write the documentation
def _float_precision_changed(self, name, old, new):

        if '%' in new:
            # got explicit format string
            fmt = new
            try:
                fmt%3.14159
            except Exception:
                raise ValueError("Precision must be int or format string, not %r"%new)
        elif new:
            # otherwise, should be an int
            try:
                i = int(new)
                assert i >= 0
            except ValueError:
                raise ValueError("Precision must be int or format string, not %r"%new)
            except AssertionError:
                raise ValueError("int precision must be non-negative, not %r"%i)

            fmt = '%%.%if'%i
            if 'numpy' in sys.modules:
                # set numpy precision if it has been imported
                import numpy
                numpy.set_printoptions(precision=i)
        else:
            # default back to repr
            fmt = '%r'
            if 'numpy' in sys.modules:
                import numpy
                # numpy default is 8
                numpy.set_printoptions(precision=8)
        self.float_format = fmt

Response: This function is called when the float precision of a single entry in a log file has changed.


Instruction:
Write a Python 3 script to
return path to any existing user config files

Response:
def user_config_files():
    """Return path to any existing user config files
    """
    return filter(os.path.exists,
                  map(os.path.expanduser, config_files))


Instruction:
Write a Python 3 function that can
do the value look like an on flag?

Response:
def flag(val):
    """Does the value look like an on/off flag?"""
    if val == 1:
        return True
    elif val == 0:
        return False
    val = str(val)
    if len(val) > 5:
        return False
    return val.upper() in ('1', '0', 'F', 'T', 'TRUE', 'FALSE', 'ON', 'OFF')


Instruction:
Make a summary of the following Python 3 code
def configure(self, argv=None, doc=None):
        env = self.env
        if argv is None:
            argv = sys.argv

        cfg_files = getattr(self, 'files', [])
        options, args = self._parseArgs(argv, cfg_files)
        # If -c --config has been specified on command line,
        # load those config files and reparse
        if getattr(options, 'files', []):
            options, args = self._parseArgs(argv, options.files)

        self.options = options
        if args:
            self.testNames = args
        if options.testNames is not None:
            self.testNames.extend(tolist(options.testNames))

        if options.py3where is not None:
            if sys.version_info >= (3,):
                options.where = options.py3where

        # `where` is an append action, so it can't have a default value
        # in the parser, or that default will always be in the list
        if not options.where:
            options.where = env.get('NOSE_WHERE', None)

        # include and exclude also
        if not options.ignoreFiles:
            options.ignoreFiles = env.get('NOSE_IGNORE_FILES', [])
        if not options.include:
            options.include = env.get('NOSE_INCLUDE', [])
        if not options.exclude:
            options.exclude = env.get('NOSE_EXCLUDE', [])

        self.addPaths = options.addPaths
        self.stopOnError = options.stopOnError
        self.verbosity = options.verbosity
        self.includeExe = options.includeExe
        self.traverseNamespace = options.traverseNamespace
        self.debug = options.debug
        self.debugLog = options.debugLog
        self.loggingConfig = options.loggingConfig
        self.firstPackageWins = options.firstPackageWins
        self.configureLogging()

        if options.where is not None:
            self.configureWhere(options.where)

        if options.testMatch:
            self.testMatch = re.compile(options.testMatch)

        if options.ignoreFiles:
            self.ignoreFiles = map(re.compile, tolist(options.ignoreFiles))
            log.info("Ignoring files matching %s", options.ignoreFiles)
        else:
            log.info("Ignoring files matching %s", self.ignoreFilesDefaultStrings)

        if options.include:
            self.include = map(re.compile, tolist(options.include))
            log.info("Including tests matching %s", options.include)

        if options.exclude:
            self.exclude = map(re.compile, tolist(options.exclude))
            log.info("Excluding tests matching %s", options.exclude)

        # When listing plugins we don't want to run them
        if not options.showPlugins:
            self.plugins.configure(options, self)
            self.plugins.begin()

Response:
Execute configure before
        collecting tests with nose. TestCollector to enable output capture and other features.


Instruction:
Can you implement a function in Python 3 that
configures logging for nose or optionally other packages.

Response:
def configureLogging(self):
        """Configure logging for nose, or optionally other packages. Any logger
        name may be set with the debug option, and that logger will be set to
        debug level and be assigned the same handler as the nose loggers, unless
        it already has a handler.
        """
        if self.loggingConfig:
            from logging.config import fileConfig
            fileConfig(self.loggingConfig)
            return

        format = logging.Formatter('%(name)s: %(levelname)s: %(message)s')
        if self.debugLog:
            handler = logging.FileHandler(self.debugLog)
        else:
            handler = logging.StreamHandler(self.logStream)
        handler.setFormatter(format)

        logger = logging.getLogger('nose')
        logger.propagate = 0

        # only add our default handler if there isn't already one there
        # this avoids annoying duplicate log messages.
        if handler not in logger.handlers:
            logger.addHandler(handler)

        # default level
        lvl = logging.WARNING
        if self.verbosity >= 5:
            lvl = 0
        elif self.verbosity >= 4:
            lvl = logging.DEBUG
        elif self.verbosity >= 3:
            lvl = logging.INFO
        logger.setLevel(lvl)

        # individual overrides
        if self.debug:
            # no blanks
            debug_loggers = [ name for name in self.debug.split(',')
                              if name ]
            for logger_name in debug_loggers:
                l = logging.getLogger(logger_name)
                l.setLevel(logging.DEBUG)
                if not l.handlers and not logger_name.startswith('nose'):
                    l.addHandler(handler)


Instruction:
Can you tell what is the following Python 3 function doing
def configureWhere(self, where):
        from nose.importer import add_path
        self.workingDir = None
        where = tolist(where)
        warned = False
        for path in where:
            if not self.workingDir:
                abs_path = absdir(path)
                if abs_path is None:
                    raise ValueError("Working directory %s not found, or "
                                     "not a directory" % path)
                log.info("Set working dir to %s", abs_path)
                self.workingDir = abs_path
                if self.addPaths and \
                       os.path.exists(os.path.join(abs_path, '__init__.py')):
                    log.info("Working directory %s is a package; "
                             "adding to sys.path" % abs_path)
                    add_path(abs_path)
                continue
            if not warned:
                warn("Use of multiple -w arguments is deprecated and "
                     "support may be removed in a future release. You can "
                     "get the same behavior by passing directories without "
                     "the -w argument on the command line, or by using the "
                     "--tests argument in a configuration file.",
                     DeprecationWarning)
            self.testNames.append(path)

Response: Configure the working directory or directories for the test run.


Instruction:
Can you generate a brief explanation for the following Python 3 code
def getParser(self, doc=None):
        if self.parser:
            return self.parser
        env = self.env
        parser = self.parserClass(doc)
        parser.add_option(
            "-V","--version", action="store_true",
            dest="version", default=False,
            help="Output nose version and exit")
        parser.add_option(
            "-p", "--plugins", action="store_true",
            dest="showPlugins", default=False,
            help="Output list of available plugins and exit. Combine with "
            "higher verbosity for greater detail")
        parser.add_option(
            "-v", "--verbose",
            action="count", dest="verbosity",
            default=self.verbosity,
            help="Be more verbose. [NOSE_VERBOSE]")
        parser.add_option(
            "--verbosity", action="store", dest="verbosity",
            metavar='VERBOSITY',
            type="int", help="Set verbosity; --verbosity=2 is "
            "the same as -v")
        parser.add_option(
            "-q", "--quiet", action="store_const", const=0, dest="verbosity",
            help="Be less verbose")
        parser.add_option(
            "-c", "--config", action="append", dest="files",
            metavar="FILES",
            help="Load configuration from config file(s). May be specified "
            "multiple times; in that case, all config files will be "
            "loaded and combined")
        parser.add_option(
            "-w", "--where", action="append", dest="where",
            metavar="WHERE",
            help="Look for tests in this directory. "
            "May be specified multiple times. The first directory passed "
            "will be used as the working directory, in place of the current "
            "working directory, which is the default. Others will be added "
            "to the list of tests to execute. [NOSE_WHERE]"
            )
        parser.add_option(
            "--py3where", action="append", dest="py3where",
            metavar="PY3WHERE",
            help="Look for tests in this directory under Python 3.x. "
            "Functions the same as 'where', but only applies if running under "
            "Python 3.x or above.  Note that, if present under 3.x, this "
            "option completely replaces any directories specified with "
            "'where', so the 'where' option becomes ineffective. "
            "[NOSE_PY3WHERE]"
            )
        parser.add_option(
            "-m", "--match", "--testmatch", action="store",
            dest="testMatch", metavar="REGEX",
            help="Files, directories, function names, and class names "
            "that match this regular expression are considered tests.  "
            "Default: %s [NOSE_TESTMATCH]" % self.testMatchPat,
            default=self.testMatchPat)
        parser.add_option(
            "--tests", action="store", dest="testNames", default=None,
            metavar='NAMES',
            help="Run these tests (comma-separated list). This argument is "
            "useful mainly from configuration files; on the command line, "
            "just pass the tests to run as additional arguments with no "
            "switch.")
        parser.add_option(
            "-l", "--debug", action="store",
            dest="debug", default=self.debug,
            help="Activate debug logging for one or more systems. "
            "Available debug loggers: nose, nose.importer, "
            "nose.inspector, nose.plugins, nose.result and "
            "nose.selector. Separate multiple names with a comma.")
        parser.add_option(
            "--debug-log", dest="debugLog", action="store",
            default=self.debugLog, metavar="FILE",
            help="Log debug messages to this file "
            "(default: sys.stderr)")
        parser.add_option(
            "--logging-config", "--log-config",
            dest="loggingConfig", action="store",
            default=self.loggingConfig, metavar="FILE",
            help="Load logging config from this file -- bypasses all other"
            " logging config settings.")
        parser.add_option(
            "-I", "--ignore-files", action="append", dest="ignoreFiles",
            metavar="REGEX",
            help="Completely ignore any file that matches this regular "
            "expression. Takes precedence over any other settings or "
            "plugins. "
            "Specifying this option will replace the default setting. "
            "Specify this option multiple times "
            "to add more regular expressions [NOSE_IGNORE_FILES]")
        parser.add_option(
            "-e", "--exclude", action="append", dest="exclude",
            metavar="REGEX",
            help="Don't run tests that match regular "
            "expression [NOSE_EXCLUDE]")
        parser.add_option(
            "-i", "--include", action="append", dest="include",
            metavar="REGEX",
            help="This regular expression will be applied to files, "
            "directories, function names, and class names for a chance "
            "to include additional tests that do not match TESTMATCH.  "
            "Specify this option multiple times "
            "to add more regular expressions [NOSE_INCLUDE]")
        parser.add_option(
            "-x", "--stop", action="store_true", dest="stopOnError",
            default=self.stopOnError,
            help="Stop running tests after the first error or failure")
        parser.add_option(
            "-P", "--no-path-adjustment", action="store_false",
            dest="addPaths",
            default=self.addPaths,
            help="Don't make any changes to sys.path when "
            "loading tests [NOSE_NOPATH]")
        parser.add_option(
            "--exe", action="store_true", dest="includeExe",
            default=self.includeExe,
            help="Look for tests in python modules that are "
            "executable. Normal behavior is to exclude executable "
            "modules, since they may not be import-safe "
            "[NOSE_INCLUDE_EXE]")
        parser.add_option(
            "--noexe", action="store_false", dest="includeExe",
            help="DO NOT look for tests in python modules that are "
            "executable. (The default on the windows platform is to "
            "do so.)")
        parser.add_option(
            "--traverse-namespace", action="store_true",
            default=self.traverseNamespace, dest="traverseNamespace",
            help="Traverse through all path entries of a namespace package")
        parser.add_option(
            "--first-package-wins", "--first-pkg-wins", "--1st-pkg-wins",
            action="store_true", default=False, dest="firstPackageWins",
            help="nose's importer will normally evict a package from sys."
            "modules if it sees a package with the same name in a different "
            "location. Set this option to disable that behavior.")

        self.plugins.loadPlugins()
        self.pluginOpts(parser)

        self.parser = parser
        return parser

Response: Get the command line option parser.


Instruction:
Given the following Python 3 function, write the documentation
def page_dumb(strng, start=0, screen_lines=25):

    out_ln  = strng.splitlines()[start:]
    screens = chop(out_ln,screen_lines-1)
    if len(screens) == 1:
        print >>io.stdout, os.linesep.join(screens[0])
    else:
        last_escape = ""
        for scr in screens[0:-1]:
            hunk = os.linesep.join(scr)
            print >>io.stdout, last_escape + hunk
            if not page_more():
                return
            esc_list = esc_re.findall(hunk)
            if len(esc_list) > 0:
                last_escape = esc_list[-1]
        print >>io.stdout, last_escape + os.linesep.join(screens[-1])

Response: Very dumb pager in Python for when nothing else works.


Instruction:
Create a Python 3 function to
detect the screen size of the current terminal.

Response:
def _detect_screen_size(use_curses, screen_lines_def):
    """Attempt to work out the number of lines on the screen.

    This is called by page(). It can raise an error (e.g. when run in the
    test suite), so it's separated out so it can easily be called in a try block.
    """
    TERM = os.environ.get('TERM',None)
    if (TERM=='xterm' or TERM=='xterm-color') and sys.platform != 'sunos5':
        local_use_curses = use_curses
    else:
        # curses causes problems on many terminals other than xterm, and
        # some termios calls lock up on Sun OS5.
        local_use_curses = False
    if local_use_curses:
        import termios
        import curses
        # There is a bug in curses, where *sometimes* it fails to properly
        # initialize, and then after the endwin() call is made, the
        # terminal is left in an unusable state.  Rather than trying to
        # check everytime for this (by requesting and comparing termios
        # flags each time), we just save the initial terminal state and
        # unconditionally reset it every time.  It's cheaper than making
        # the checks.
        term_flags = termios.tcgetattr(sys.stdout)

        # Curses modifies the stdout buffer size by default, which messes
        # up Python's normal stdout buffering.  This would manifest itself
        # to IPython users as delayed printing on stdout after having used
        # the pager.
        #
        # We can prevent this by manually setting the NCURSES_NO_SETBUF
        # environment variable.  For more details, see:
        # http://bugs.python.org/issue10144
        NCURSES_NO_SETBUF = os.environ.get('NCURSES_NO_SETBUF', None)
        os.environ['NCURSES_NO_SETBUF'] = ''

        # Proceed with curses initialization
        scr = curses.initscr()
        screen_lines_real,screen_cols = scr.getmaxyx()
        curses.endwin()

        # Restore environment
        if NCURSES_NO_SETBUF is None:
            del os.environ['NCURSES_NO_SETBUF']
        else:
            os.environ['NCURSES_NO_SETBUF'] = NCURSES_NO_SETBUF

        # Restore terminal state in case endwin() didn't.
        termios.tcsetattr(sys.stdout,termios.TCSANOW,term_flags)
        # Now we have what we needed: the screen size in rows/columns
        return screen_lines_real
        #print '***Screen size:',screen_lines_real,'lines x',\
        #screen_cols,'columns.' # dbg
    else:
        return screen_lines_def


Instruction:
Write a Python 3 script for
printing a string through a pager command.

Response:
def page(strng, start=0, screen_lines=0, pager_cmd=None):
    """Print a string, piping through a pager after a certain length.

    The screen_lines parameter specifies the number of *usable* lines of your
    terminal screen (total lines minus lines you need to reserve to show other
    information).

    If you set screen_lines to a number <=0, page() will try to auto-determine
    your screen size and will only use up to (screen_size+screen_lines) for
    printing, paging after that. That is, if you want auto-detection but need
    to reserve the bottom 3 lines of the screen, use screen_lines = -3, and for
    auto-detection without any lines reserved simply use screen_lines = 0.

    If a string won't fit in the allowed lines, it is sent through the
    specified pager command. If none given, look for PAGER in the environment,
    and ultimately default to less.

    If no system pager works, the string is sent through a 'dumb pager'
    written in python, very simplistic.
    """

    # Some routines may auto-compute start offsets incorrectly and pass a
    # negative value.  Offset to 0 for robustness.
    start = max(0, start)

    # first, try the hook
    ip = ipapi.get()
    if ip:
        try:
            ip.hooks.show_in_pager(strng)
            return
        except TryNext:
            pass

    # Ugly kludge, but calling curses.initscr() flat out crashes in emacs
    TERM = os.environ.get('TERM','dumb')
    if TERM in ['dumb','emacs'] and os.name != 'nt':
        print strng
        return
    # chop off the topmost part of the string we don't want to see
    str_lines = strng.splitlines()[start:]
    str_toprint = os.linesep.join(str_lines)
    num_newlines = len(str_lines)
    len_str = len(str_toprint)

    # Dumb heuristics to guesstimate number of on-screen lines the string
    # takes.  Very basic, but good enough for docstrings in reasonable
    # terminals. If someone later feels like refining it, it's not hard.
    numlines = max(num_newlines,int(len_str/80)+1)

    screen_lines_def = get_terminal_size()[1]

    # auto-determine screen size
    if screen_lines <= 0:
        try:
            screen_lines += _detect_screen_size(use_curses, screen_lines_def)
        except (TypeError, UnsupportedOperation):
            print >>io.stdout, str_toprint
            return

    #print 'numlines',numlines,'screenlines',screen_lines  # dbg
    if numlines <= screen_lines :
        #print '*** normal print'  # dbg
        print >>io.stdout, str_toprint
    else:
        # Try to open pager and default to internal one if that fails.
        # All failure modes are tagged as 'retval=1', to match the return
        # value of a failed system command.  If any intermediate attempt
        # sets retval to 1, at the end we resort to our own page_dumb() pager.
        pager_cmd = get_pager_cmd(pager_cmd)
        pager_cmd += ' ' + get_pager_start(pager_cmd,start)
        if os.name == 'nt':
            if pager_cmd.startswith('type'):
                # The default WinXP 'type' command is failing on complex strings.
                retval = 1
            else:
                tmpname = tempfile.mktemp('.txt')
                tmpfile = open(tmpname,'wt')
                tmpfile.write(strng)
                tmpfile.close()
                cmd = "%s < %s" % (pager_cmd,tmpname)
                if os.system(cmd):
                  retval = 1
                else:
                  retval = None
                os.remove(tmpname)
        else:
            try:
                retval = None
                # if I use popen4, things hang. No idea why.
                #pager,shell_out = os.popen4(pager_cmd)
                pager = os.popen(pager_cmd,'w')
                pager.write(strng)
                pager.close()
                retval = pager.close()  # success returns None
            except IOError,msg:  # broken pipe when user quits
                if msg.args == (32,'Broken pipe'):
                    retval = None
                else:
                    retval = 1
            except OSError:
                # Other strange problems, sometimes seen in Win2k/cygwin
                retval = 1
        if retval is not None:
            page_dumb(strng,screen_lines=screen_lines)


Instruction:
Can you create a Python 3 function that
pages a file using a pager command and starting line.

Response:
def page_file(fname, start=0, pager_cmd=None):
    """Page a file, using an optional pager command and starting line.
    """

    pager_cmd = get_pager_cmd(pager_cmd)
    pager_cmd += ' ' + get_pager_start(pager_cmd,start)

    try:
        if os.environ['TERM'] in ['emacs','dumb']:
            raise EnvironmentError
        system(pager_cmd + ' ' + fname)
    except:
        try:
            if start > 0:
                start -= 1
            page(open(fname).read(),start)
        except:
            print 'Unable to show file',`fname`


Instruction:
Implement a Python 3 function for
returning a pager command.

Response:
def get_pager_cmd(pager_cmd=None):
    """Return a pager command.

    Makes some attempts at finding an OS-correct one.
    """
    if os.name == 'posix':
        default_pager_cmd = 'less -r'  # -r for color control sequences
    elif os.name in ['nt','dos']:
        default_pager_cmd = 'type'

    if pager_cmd is None:
        try:
            pager_cmd = os.environ['PAGER']
        except:
            pager_cmd = default_pager_cmd
    return pager_cmd


Instruction:
Write a Python 3 script for
returning the string for paging files with an offset.

Response:
def get_pager_start(pager, start):
    """Return the string for paging files with an offset.

    This is the '+N' argument which less and more (under Unix) accept.
    """

    if pager in ['less','more']:
        if start:
            start_string = '+' + str(start)
        else:
            start_string = ''
    else:
        start_string = ''
    return start_string


Instruction:
Write a Python 3 script to
print a string snipping the midsection to fit in width.

Response:
def snip_print(str,width = 75,print_full = 0,header = ''):
    """Print a string snipping the midsection to fit in width.

    print_full: mode control:
      - 0: only snip long strings
      - 1: send to page() directly.
      - 2: snip long strings and ask for full length viewing with page()
    Return 1 if snipping was necessary, 0 otherwise."""

    if print_full == 1:
        page(header+str)
        return 0

    print header,
    if len(str) < width:
        print str
        snip = 0
    else:
        whalf = int((width -5)/2)
        print str[:whalf] + ' <...> ' + str[-whalf:]
        snip = 1
    if snip and print_full == 2:
        if raw_input(header+' Snipped. View (y/n)? [N]').lower() == 'y':
            page(str)
    return snip


Instruction:
How would you code a function in Python 3 to
execute a function reps times and return a tuple with the elapsed total CPU time in seconds the time per call and the output.

Response:
def timings_out(reps,func,*args,**kw):
    """timings_out(reps,func,*args,**kw) -> (t_total,t_per_call,output)

    Execute a function reps times, return a tuple with the elapsed total
    CPU time in seconds, the time per call and the function's output.

    Under Unix, the return value is the sum of user+system time consumed by
    the process, computed via the resource module.  This prevents problems
    related to the wraparound effect which the time.clock() function has.

    Under Windows the return value is in wall clock seconds. See the
    documentation for the time module for more details."""

    reps = int(reps)
    assert reps >=1, 'reps must be >= 1'
    if reps==1:
        start = clock()
        out = func(*args,**kw)
        tot_time = clock()-start
    else:
        rng = xrange(reps-1) # the last time is executed separately to store output
        start = clock()
        for dummy in rng: func(*args,**kw)
        out = func(*args,**kw)  # one last time
        tot_time = clock()-start
    av_time = tot_time / reps
    return tot_time,av_time,out


Instruction:
Can you write a function in Python 3 where it
executes a function reps times and return a tuple with the elapsed total CPU time in seconds and the time per call.

Response:
def timings(reps,func,*args,**kw):
    """timings(reps,func,*args,**kw) -> (t_total,t_per_call)

    Execute a function reps times, return a tuple with the elapsed total CPU
    time in seconds and the time per call. These are just the first two values
    in timings_out()."""

    return timings_out(reps,func,*args,**kw)[0:2]


Instruction:
Given the following Python 3 function, write the documentation
def print_display_png(o):
    s = latex(o, mode='plain')
    s = s.strip('$')
    # As matplotlib does not support display style, dvipng backend is
    # used here.
    png = latex_to_png('$$%s$$' % s, backend='dvipng')
    return png

Response: A function to display sympy expression using display style LaTeX in PNG.


Instruction:
Can you generate the documentation for the following Python 3 function
def can_print_latex(o):
    import sympy
    if isinstance(o, (list, tuple, set, frozenset)):
        return all(can_print_latex(i) for i in o)
    elif isinstance(o, dict):
        return all((isinstance(i, basestring) or can_print_latex(i)) and can_print_latex(o[i]) for i in o)
    elif isinstance(o,(sympy.Basic, sympy.matrices.Matrix, int, long, float)):
        return True
    return False

Response: Return True if LaTeX can print the given object.


Instruction:
Given the following Python 3 function, write the documentation
def print_latex(o):
    if can_print_latex(o):
        s = latex(o, mode='plain')
        s = s.replace('\\dag','\\dagger')
        s = s.strip('$')
        return '$$%s$$' % s
    # Fallback to the string printer
    return None

Response:
A function to generate the latex representation of sympy
    expressions.


Instruction:
Can you implement a function in Python 3 that
loads the extension in IPython.

Response:
def load_ipython_extension(ip):
    """Load the extension in IPython."""
    import sympy

    # sympyprinting extension has been moved to SymPy as of 0.7.2, if it
    # exists there, warn the user and import it
    try:
        import sympy.interactive.ipythonprinting
    except ImportError:
        pass
    else:
        warnings.warn("The sympyprinting extension in IPython is deprecated, "
            "use sympy.interactive.ipythonprinting")
        ip.extension_manager.load_extension('sympy.interactive.ipythonprinting')
        return

    global _loaded
    if not _loaded:
        plaintext_formatter = ip.display_formatter.formatters['text/plain']

        for cls in (object, str):
            plaintext_formatter.for_type(cls, print_basic_unicode)

        printable_containers = [list, tuple]

        # set and frozen set were broken with SymPy's latex() function, but
        # was fixed in the 0.7.1-git development version. See
        # http://code.google.com/p/sympy/issues/detail?id=3062.
        if sympy.__version__ > '0.7.1':
            printable_containers += [set, frozenset]
        else:
            plaintext_formatter.for_type(cls, print_basic_unicode)

        plaintext_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_basic_unicode
        )
        plaintext_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_basic_unicode
        )

        png_formatter = ip.display_formatter.formatters['image/png']

        png_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_png
        )
        png_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_display_png
        )
        for cls in [dict, int, long, float] + printable_containers:
            png_formatter.for_type(cls, print_png)

        latex_formatter = ip.display_formatter.formatters['text/latex']
        latex_formatter.for_type_by_name(
            'sympy.core.basic', 'Basic', print_latex
        )
        latex_formatter.for_type_by_name(
            'sympy.matrices.matrices', 'Matrix', print_latex
        )

        for cls in printable_containers:
            # Use LaTeX only if every element is printable by latex
            latex_formatter.for_type(cls, print_latex)

        _loaded = True


Instruction:
Here you have a function in Python 3, explain what it does
def str2tokens(string, delimiter):

    token_list = [token.strip() for token in string.split(delimiter)]
    return token_list

Response: Convert a string to a list of tokens


Instruction:
Can you tell what is the following Python 3 function doing
def str2tokenstags(string, delimiter):

    token_list = [token.strip() for token in string.split(delimiter)]
    return token_list

Response: Convert a string to a list of tokens.


Instruction:
Can you generate the documentation for the following Python 3 function
def add_options(self, parser, env=None):
        # FIXME raise deprecation warning if wasn't called by wrapper
        if env is None:
            env = os.environ
        try:
            self.options(parser, env)
            self.can_configure = True
        except OptionConflictError, e:
            warn("Plugin %s has conflicting option string: %s and will "
                 "be disabled" % (self, e), RuntimeWarning)
            self.enabled = False
            self.can_configure = False

Response: Add options to the object.


Instruction:
Here you have a function in Python 3, explain what it does
def options(self, parser, env):
        env_opt = 'NOSE_WITH_%s' % self.name.upper()
        env_opt = env_opt.replace('-', '_')
        parser.add_option("--with-%s" % self.name,
                          action="store_true",
                          dest=self.enableOpt,
                          default=env.get(env_opt),
                          help="Enable plugin %s: %s [%s]" %
                          (self.__class__.__name__, self.help(), env_opt))

Response:
Register commandline options.

        Implement this method for normal options behavior with protection from
        OptionConflictErrors. If you override this method and want the default
        --with-$name option to be registered, be sure to call super().


Instruction:
Write a Python 3 script to
configure the base plugin and system based on selected options.

Response:
def configure(self, options, conf):
        """Configure the plugin and system, based on selected options.

        The base plugin class sets the plugin to enabled if the enable option
        for the plugin (self.enableOpt) is true.
        """
        if not self.can_configure:
            return
        self.conf = conf
        if hasattr(options, self.enableOpt):
            self.enabled = getattr(options, self.enableOpt)


Instruction:
Make a summary of the following Python 3 code
def validate_string_list(lst):
    if not isinstance(lst, list):
        raise ValueError('input %r must be a list' % lst)
    for x in lst:
        if not isinstance(x, basestring):
            raise ValueError('element %r in list must be a string' % x)

Response: Validate that the input is a list of strings. Raises ValueError if not.


Instruction:
Can you implement a function in Python 3 that
validates that the input is a dict with string keys and values. Raises ValueError if not.

Response:
def validate_string_dict(dct):
    """Validate that the input is a dict with string keys and values.

    Raises ValueError if not."""
    for k,v in dct.iteritems():
        if not isinstance(k, basestring):
            raise ValueError('key %r in dict must be a string' % k)
        if not isinstance(v, basestring):
            raise ValueError('value %r in dict must be a string' % v)


Instruction:
How would you explain what the following Python 3 function does
def _run_loop(self):
        while True:
            try:
                self.ioloop.start()
            except ZMQError as e:
                if e.errno == errno.EINTR:
                    continue
                else:
                    raise
            except Exception:
                if self._exiting:
                    break
                else:
                    raise
            else:
                break

Response: Run the loop in the poller


Instruction:
Write a Python 3 function for
queuing a message to be sent from the IOLoop s thread.

Response:
def _queue_send(self, msg):
        """Queue a message to be sent from the IOLoop's thread.

        Parameters
        ----------
        msg : message to send

        This is threadsafe, as it uses IOLoop.add_callback to give the loop's
        thread control of the action.
        """
        def thread_send():
            self.session.send(self.stream, msg)
        self.ioloop.add_callback(thread_send)


Instruction:
Explain what the following Python 3 code does
def _handle_recv(self, msg):
        ident,smsg = self.session.feed_identities(msg)
        self.call_handlers(self.session.unserialize(smsg))

Response:
callback for stream. on_recv

        unpacks message and calls handlers with it.


Instruction:
Make a summary of the following Python 3 code
def run(self):
        self.socket = self.context.socket(zmq.DEALER)
        self.socket.setsockopt(zmq.IDENTITY, self.session.bsession)
        self.socket.connect('tcp://%s:%i' % self.address)
        self.stream = zmqstream.ZMQStream(self.socket, self.ioloop)
        self.stream.on_recv(self._handle_recv)
        self._run_loop()
        try:
            self.socket.close()
        except:
            pass

Response: The main activity. Call start() instead.


Instruction:
How would you code a function in Python 3 to
execute a Python code in the kernel and return the message_id.

Response:
def execute(self, code, silent=False,
                user_variables=None, user_expressions=None, allow_stdin=None):
        """Execute code in the kernel.

        Parameters
        ----------
        code : str
            A string of Python code.

        silent : bool, optional (default False)
            If set, the kernel will execute the code as quietly possible.

        user_variables : list, optional
            A list of variable names to pull from the user's namespace.  They
            will come back as a dict with these names as keys and their
            :func:`repr` as values.

        user_expressions : dict, optional
            A dict with string keys and  to pull from the user's
            namespace.  They will come back as a dict with these names as keys
            and their :func:`repr` as values.

        allow_stdin : bool, optional
            Flag for
            A dict with string keys and  to pull from the user's
            namespace.  They will come back as a dict with these names as keys
            and their :func:`repr` as values.

        Returns
        -------
        The msg_id of the message sent.
        """
        if user_variables is None:
            user_variables = []
        if user_expressions is None:
            user_expressions = {}
        if allow_stdin is None:
            allow_stdin = self.allow_stdin

        # Don't waste network traffic if inputs are invalid
        if not isinstance(code, basestring):
            raise ValueError('code %r must be a string' % code)
        validate_string_list(user_variables)
        validate_string_dict(user_expressions)

        # Create class for content/msg creation. Related to, but possibly
        # not in Session.
        content = dict(code=code, silent=silent,
                       user_variables=user_variables,
                       user_expressions=user_expressions,
                       allow_stdin=allow_stdin,
                       )
        msg = self.session.msg('execute_request', content)
        self._queue_send(msg)
        return msg['header']['msg_id']


Instruction:
Can you generate the documentation for the following Python 3 function
def object_info(self, oname, detail_level=0):
        content = dict(oname=oname, detail_level=detail_level)
        msg = self.session.msg('object_info_request', content)
        self._queue_send(msg)
        return msg['header']['msg_id']

Response: Get metadata about an object.


Instruction:
How would you code a function in Python 3 to
get entries from the history list.

Response:
def history(self, raw=True, output=False, hist_access_type='range', **kwargs):
        """Get entries from the history list.

        Parameters
        ----------
        raw : bool
            If True, return the raw input.
        output : bool
            If True, then return the output as well.
        hist_access_type : str
            'range' (fill in session, start and stop params), 'tail' (fill in n)
             or 'search' (fill in pattern param).

        session : int
            For a range request, the session from which to get lines. Session
            numbers are positive integers; negative ones count back from the
            current session.
        start : int
            The first line number of a history range.
        stop : int
            The final (excluded) line number of a history range.

        n : int
            The number of lines of history to get for a tail request.

        pattern : str
            The glob-syntax pattern for a search request.

        Returns
        -------
        The msg_id of the message sent.
        """
        content = dict(raw=raw, output=output, hist_access_type=hist_access_type,
                                                                    **kwargs)
        msg = self.session.msg('history_request', content)
        self._queue_send(msg)
        return msg['header']['msg_id']


Instruction:
Create a Python 3 function for
requesting an immediate kernel shutdown.

Response:
def shutdown(self, restart=False):
        """Request an immediate kernel shutdown.

        Upon receipt of the (empty) reply, client code can safely assume that
        the kernel has shut down and it's safe to forcefully terminate it if
        it's still alive.

        The kernel will send the reply via a function registered with Python's
        atexit module, ensuring it's truly done as the kernel is done with all
        normal operation.
        """
        # Send quit message to kernel. Once we implement kernel-side setattr,
        # this should probably be done that way, but for now this will do.
        msg = self.session.msg('shutdown_request', {'restart':restart})
        self._queue_send(msg)
        return msg['header']['msg_id']


Instruction:
Explain what the following Python 3 code does
def flush(self, timeout=1.0):
        # We do the IOLoop callback process twice to ensure that the IOLoop
        # gets to perform at least one full poll.
        stop_time = time.time() + timeout
        for i in xrange(2):
            self._flushed = False
            self.ioloop.add_callback(self._flush)
            while not self._flushed and time.time() < stop_time:
                time.sleep(0.01)

Response: Flushes all pending messages on the SUB channel.


Instruction:
Create a Python 3 function to
send a string of raw input to the kernel.

Response:
def input(self, string):
        """Send a string of raw input to the kernel."""
        content = dict(value=string)
        msg = self.session.msg('input_reply', content)
        self._queue_send(msg)


Instruction:
How would you explain what the following Python 3 function does
def _poll(self, start_time):

        until_dead = self.time_to_dead - (time.time() - start_time)
        # ensure poll at least once
        until_dead = max(until_dead, 1e-3)
        events = []
        while True:
            try:
                events = self.poller.poll(1000 * until_dead)
            except ZMQError as e:
                if e.errno == errno.EINTR:
                    # ignore interrupts during heartbeat
                    # this may never actually happen
                    until_dead = self.time_to_dead - (time.time() - start_time)
                    until_dead = max(until_dead, 1e-3)
                    pass
                else:
                    raise
            except Exception:
                if self._exiting:
                    break
                else:
                    raise
            else:
                break
        return events

Response:
poll for heartbeat replies until we reach self. time_to_dead
alid


Instruction:
How would you explain what the following Python 3 function does
def run(self):
        self._create_socket()
        self._running = True
        self._beating = True

        while self._running:
            if self._pause:
                # just sleep, and skip the rest of the loop
                time.sleep(self.time_to_dead)
                continue

            since_last_heartbeat = 0.0
            # io.rprint('Ping from HB channel') # dbg
            # no need to catch EFSM here, because the previous event was
            # either a recv or connect, which cannot be followed by EFSM
            self.socket.send(b'ping')
            request_time = time.time()
            ready = self._poll(request_time)
            if ready:
                self._beating = True
                # the poll above guarantees we have something to recv
                self.socket.recv()
                # sleep the remainder of the cycle
                remainder = self.time_to_dead - (time.time() - request_time)
                if remainder > 0:
                    time.sleep(remainder)
                continue
            else:
                # nothing was received within the time limit, signal heart failure
                self._beating = False
                since_last_heartbeat = time.time() - request_time
                self.call_handlers(since_last_heartbeat)
                # and close/reopen the socket, because the REQ/REP cycle has been broken
                self._create_socket()
                continue
        try:
            self.socket.close()
        except:
            pass

Response: The main activity. Call start() instead.


Instruction:
Create a Python 3 function to
am the heartbeat running and responsive and not paused?

Response:
def is_beating(self):
        """Is the heartbeat running and responsive (and not paused)."""
        if self.is_alive() and not self._pause and self._beating:
            return True
        else:
            return False


Instruction:
Explain what the following Python 3 code does
def start_channels(self, shell=True, sub=True, stdin=True, hb=True):
        if shell:
            self.shell_channel.start()
        if sub:
            self.sub_channel.start()
        if stdin:
            self.stdin_channel.start()
            self.shell_channel.allow_stdin = True
        else:
            self.shell_channel.allow_stdin = False
        if hb:
            self.hb_channel.start()

Response: Starts the channels for this kernel.


Instruction:
Implement a function in Python 3 to
stop all the running channels for this kernel.

Response:
def stop_channels(self):
        """Stops all the running channels for this kernel.
        """
        if self.shell_channel.is_alive():
            self.shell_channel.stop()
        if self.sub_channel.is_alive():
            self.sub_channel.stop()
        if self.stdin_channel.is_alive():
            self.stdin_channel.stop()
        if self.hb_channel.is_alive():
            self.hb_channel.stop()


Instruction:
How would you explain what the following Python 3 function does
def channels_running(self):
        return (self.shell_channel.is_alive() or self.sub_channel.is_alive() or
                self.stdin_channel.is_alive() or self.hb_channel.is_alive())

Response: Return True if any of the channels created and running?


Instruction:
Can you tell what is the following Python 3 function doing
def cleanup_connection_file(self):
        if self._connection_file_written:
            # cleanup connection files on full shutdown of kernel we started
            self._connection_file_written = False
            try:
                os.remove(self.connection_file)
            except OSError:
                pass

Response: cleanup connection file if we wrote it *if we wrote it*


Instruction:
Can you generate a brief explanation for the following Python 3 code
def load_connection_file(self):
        with open(self.connection_file) as f:
            cfg = json.loads(f.read())

        self.ip = cfg['ip']
        self.shell_port = cfg['shell_port']
        self.stdin_port = cfg['stdin_port']
        self.iopub_port = cfg['iopub_port']
        self.hb_port = cfg['hb_port']
        self.session.key = str_to_bytes(cfg['key'])

Response: load connection info from JSON dict in self. connection_file


Instruction:
Can you create a Python 3 function that
writes the connection info to the connection file

Response:
def write_connection_file(self):
        """write connection info to JSON dict in self.connection_file"""
        if self._connection_file_written:
            return
        self.connection_file,cfg = write_connection_file(self.connection_file,
            ip=self.ip, key=self.session.key,
            stdin_port=self.stdin_port, iopub_port=self.iopub_port,
            shell_port=self.shell_port, hb_port=self.hb_port)
        # write_connection_file also sets default ports:
        self.shell_port = cfg['shell_port']
        self.stdin_port = cfg['stdin_port']
        self.iopub_port = cfg['iopub_port']
        self.hb_port = cfg['hb_port']

        self._connection_file_written = True


Instruction:
Write a Python 3 script for
starting a kernel process and configures the manager to use it.

Response:
def start_kernel(self, **kw):
        """Starts a kernel process and configures the manager to use it.

        If random ports (port=0) are being used, this method must be called
        before the channels are created.

        Parameters:
        -----------
        launcher : callable, optional (default None)
             A custom function for launching the kernel process (generally a
             wrapper around ``entry_point.base_launch_kernel``). In most cases,
             it should not be necessary to use this parameter.

        **kw : optional
             See respective options for IPython and Python kernels.
        """
        if self.ip not in LOCAL_IPS:
            raise RuntimeError("Can only launch a kernel on a local interface. "
                               "Make sure that the '*_address' attributes are "
                               "configured properly. "
                               "Currently valid addresses are: %s"%LOCAL_IPS
                               )

        # write connection file / get default ports
        self.write_connection_file()

        self._launch_args = kw.copy()
        launch_kernel = kw.pop('launcher', None)
        if launch_kernel is None:
            from ipkernel import launch_kernel
        self.kernel = launch_kernel(fname=self.connection_file, **kw)


Instruction:
Implement a function in Python 3 to
stop the kernel process and kills the kernel process if possible.

Response:
def shutdown_kernel(self, restart=False):
        """ Attempts to the stop the kernel process cleanly. If the kernel
        cannot be stopped, it is killed, if possible.
        """
        # FIXME: Shutdown does not work on Windows due to ZMQ errors!
        if sys.platform == 'win32':
            self.kill_kernel()
            return

        # Pause the heart beat channel if it exists.
        if self._hb_channel is not None:
            self._hb_channel.pause()

        # Don't send any additional kernel kill messages immediately, to give
        # the kernel a chance to properly execute shutdown actions. Wait for at
        # most 1s, checking every 0.1s.
        self.shell_channel.shutdown(restart=restart)
        for i in range(10):
            if self.is_alive:
                time.sleep(0.1)
            else:
                break
        else:
            # OK, we've waited long enough.
            if self.has_kernel:
                self.kill_kernel()

        if not restart and self._connection_file_written:
            # cleanup connection files on full shutdown of kernel we started
            self._connection_file_written = False
            try:
                os.remove(self.connection_file)
            except IOError:
                pass


Instruction:
Create a Python 3 function to
restart a kernel with the arguments that were used to launch it.

Response:
def restart_kernel(self, now=False, **kw):
        """Restarts a kernel with the arguments that were used to launch it.

        If the old kernel was launched with random ports, the same ports will be
        used for the new kernel.

        Parameters
        ----------
        now : bool, optional
            If True, the kernel is forcefully restarted *immediately*, without
            having a chance to do any cleanup action.  Otherwise the kernel is
            given 1s to clean up before a forceful restart is issued.

            In all cases the kernel is restarted, the only difference is whether
            it is given a chance to perform a clean shutdown or not.

        **kw : optional
            Any options specified here will replace those used to launch the
            kernel.
        """
        if self._launch_args is None:
            raise RuntimeError("Cannot restart the kernel. "
                               "No previous call to 'start_kernel'.")
        else:
            # Stop currently running kernel.
            if self.has_kernel:
                if now:
                    self.kill_kernel()
                else:
                    self.shutdown_kernel(restart=True)

            # Start new kernel.
            self._launch_args.update(kw)
            self.start_kernel(**self._launch_args)

            # FIXME: Messages get dropped in Windows due to probable ZMQ bug
            # unless there is some delay here.
            if sys.platform == 'win32':
                time.sleep(0.2)


Instruction:
Can you create a Python 3 function that
kills the running kernel.

Response:
def kill_kernel(self):
        """ Kill the running kernel. """
        if self.has_kernel:
            # Pause the heart beat channel if it exists.
            if self._hb_channel is not None:
                self._hb_channel.pause()

            # Attempt to kill the kernel.
            try:
                self.kernel.kill()
            except OSError, e:
                # In Windows, we will get an Access Denied error if the process
                # has already terminated. Ignore it.
                if sys.platform == 'win32':
                    if e.winerror != 5:
                        raise
                # On Unix, we may get an ESRCH error if the process has already
                # terminated. Ignore it.
                else:
                    from errno import ESRCH
                    if e.errno != ESRCH:
                        raise
            self.kernel = None
        else:
            raise RuntimeError("Cannot kill kernel. No kernel is running!")


Instruction:
Can you write a function in Python 3 where it
interrupts the kernel. Unlike ``signal_kernel``, this operation is well supported on all platforms.

Response:
def interrupt_kernel(self):
        """ Interrupts the kernel. Unlike ``signal_kernel``, this operation is
        well supported on all platforms.
        """
        if self.has_kernel:
            if sys.platform == 'win32':
                from parentpoller import ParentPollerWindows as Poller
                Poller.send_interrupt(self.kernel.win32_interrupt_event)
            else:
                self.kernel.send_signal(signal.SIGINT)
        else:
            raise RuntimeError("Cannot interrupt kernel. No kernel is running!")


Instruction:
Implement a Python 3 function for
sending a signal to the kernel.

Response:
def signal_kernel(self, signum):
        """ Sends a signal to the kernel. Note that since only SIGTERM is
        supported on Windows, this function is only useful on Unix systems.
        """
        if self.has_kernel:
            self.kernel.send_signal(signum)
        else:
            raise RuntimeError("Cannot signal kernel. No kernel is running!")


Instruction:
Create a Python 3 function to
am the kernel process still running?

Response:
def is_alive(self):
        """Is the kernel process still running?"""
        if self.has_kernel:
            if self.kernel.poll() is None:
                return True
            else:
                return False
        elif self._hb_channel is not None:
            # We didn't start the kernel with this KernelManager so we
            # use the heartbeat.
            return self._hb_channel.is_beating()
        else:
            # no heartbeat and not local, we can't tell if it's running,
            # so naively return True
            return True


Instruction:
Write a Python 3 function for
getting the REQ socket channel object to make requests of the kernel.

Response:
def shell_channel(self):
        """Get the REQ socket channel object to make requests of the kernel."""
        if self._shell_channel is None:
            self._shell_channel = self.shell_channel_class(self.context,
                                                         self.session,
                                                         (self.ip, self.shell_port))
        return self._shell_channel


Instruction:
Explain what the following Python 3 code does
def sub_channel(self):
        if self._sub_channel is None:
            self._sub_channel = self.sub_channel_class(self.context,
                                                       self.session,
                                                       (self.ip, self.iopub_port))
        return self._sub_channel

Response: Get the SUB socket channel object.


Instruction:
Can you implement a function in Python 3 that
gets the REP socket channel object to handle stdin ( raw_input.

Response:
def stdin_channel(self):
        """Get the REP socket channel object to handle stdin (raw_input)."""
        if self._stdin_channel is None:
            self._stdin_channel = self.stdin_channel_class(self.context,
                                                       self.session,
                                                       (self.ip, self.stdin_port))
        return self._stdin_channel


Instruction:
Implement a Python 3 function for
getting the heartbeat socket channel object to check that the the kernel is alive.

Response:
def hb_channel(self):
        """Get the heartbeat socket channel object to check that the
        kernel is alive."""
        if self._hb_channel is None:
            self._hb_channel = self.hb_channel_class(self.context,
                                                       self.session,
                                                       (self.ip, self.hb_port))
        return self._hb_channel


Instruction:
Write a Python 3 function for
binding an Engine s Kernel to be used as a full IPython kernel.

Response:
def bind_kernel(**kwargs):
    """Bind an Engine's Kernel to be used as a full IPython kernel.

    This allows a running Engine to be used simultaneously as a full IPython kernel
    with the QtConsole or other frontends.

    This function returns immediately.
    """
    from IPython.zmq.ipkernel import IPKernelApp
    from IPython.parallel.apps.ipengineapp import IPEngineApp

    # first check for IPKernelApp, in which case this should be a no-op
    # because there is already a bound kernel
    if IPKernelApp.initialized() and isinstance(IPKernelApp._instance, IPKernelApp):
        return

    if IPEngineApp.initialized():
        try:
            app = IPEngineApp.instance()
        except MultipleInstanceError:
            pass
        else:
            return app.bind_kernel(**kwargs)

    raise RuntimeError("bind_kernel be called from an IPEngineApp instance")


Instruction:
Write a Python 3 function that can
emit a debugging message depending on the debugging level.

Response:
def debug(self, level, message):
        """
        Emit a debugging message depending on the debugging level.

        :param level: The debugging level.
        :param message: The message to emit.
        """

        if self._debug >= level:
            print(message, file=sys.stderr)


Instruction:
How would you implement a function in Python 3 that
retrieves the extension classes in proper priority order.

Response:
def _get_extension_classes(cls):
        """
        Retrieve the extension classes in priority order.

        :returns: A list of extension classes, in proper priority
                  order.
        """

        if cls._extension_classes is None:
            exts = {}

            # Iterate over the entrypoints
            for ext in entry.points[NAMESPACE_EXTENSIONS]:
                exts.setdefault(ext.priority, [])
                exts[ext.priority].append(ext)

            # Save the list of extension classes
            cls._extension_classes = list(utils.iter_prio_dict(exts))

        return cls._extension_classes


Instruction:
How would you explain what the following Python 3 function does
def prepare(cls, parser):

        debugger = ExtensionDebugger('prepare')

        for ext in cls._get_extension_classes():
            with debugger(ext):
                ext.prepare(parser)

Response: Prepare all the extensions.


Instruction:
Write a Python 3 function for
initializing the extensions that are being activated and returns an instance of the class that is returned by the activate method.

Response:
def activate(cls, ctxt, args):
        """
        Initialize the extensions.  This loops over each extension
        invoking its ``activate()`` method; those extensions that
        return an object are considered "activated" and will be called
        at later phases of extension processing.

        :param ctxt: An instance of ``timid.context.Context``.
        :param args: An instance of ``argparse.Namespace`` containing
                     the result of processing command line arguments.

        :returns: An instance of ``ExtensionSet``.
        """

        debugger = ExtensionDebugger('activate')

        exts = []
        for ext in cls._get_extension_classes():
            # Not using debugger as a context manager here, because we
            # want to know about the exception even if we're ignoring
            # it...but we need to notify which extension is being
            # processed!
            debugger(ext)

            try:
                # Check if the extension is being activated
                obj = ext.activate(ctxt, args)
            except Exception:
                # Hmmm, failed to activate; handle the error
                exc_info = sys.exc_info()
                if not debugger.__exit__(*exc_info):
                    six.reraise(*exc_info)
            else:
                # OK, if the extension is activated, use it
                if obj is not None:
                    exts.append(obj)
                    debugger.debug(2, 'Activating extension "%s.%s"' %
                                   (ext.__module__, ext.__name__))

        # Initialize and return the ExtensionSet
        return cls(exts)


Instruction:
Write a Python 3 function that can
call after adding them to the list of test steps.

Response:
def read_steps(self, ctxt, steps):
        """
        Called after reading steps, prior to adding them to the list of
        test steps.  Extensions are able to alter the list (in place).

        :param ctxt: An instance of ``timid.context.Context``.
        :param steps: A list of ``timid.steps.Step`` instances.

        :returns: The ``steps`` parameter, for convenience.
        """

        debugger = ExtensionDebugger('read_steps')

        for ext in self.exts:
            with debugger(ext):
                ext.read_steps(ctxt, steps)

        # Convenience return
        return steps


Instruction:
Can you implement a function in Python 3 that
calls prior to executing a step. Returns True if the step is to be skipped False otherwise.

Response:
def pre_step(self, ctxt, step, idx):
        """
        Called prior to executing a step.

        :param ctxt: An instance of ``timid.context.Context``.
        :param step: An instance of ``timid.steps.Step`` describing
                     the step to be executed.
        :param idx: The index of the step in the list of steps.

        :returns: A ``True`` value if the step is to be skipped,
                  ``False`` otherwise.
        """

        debugger = ExtensionDebugger('pre_step')

        for ext in self.exts:
            with debugger(ext):
                if ext.pre_step(ctxt, step, idx):
                    # Step must be skipped
                    debugger.debug(3, 'Skipping step %d' % idx)
                    return True

        return False


Instruction:
How would you explain what the following Python 3 function does
def post_step(self, ctxt, step, idx, result):

        debugger = ExtensionDebugger('post_step')

        for ext in self.exts:
            with debugger(ext):
                ext.post_step(ctxt, step, idx, result)

        # Convenience return
        return result

Response: Called after executing a step.