Instruction:
Can you tell what is the following Python 3 function doing
def mutate(field, strat_name_or_cls, num=100, at_once=1, yield_changed=False):
    import pfp.fuzz.rand as rand

    init()

    strat = get_strategy(strat_name_or_cls)
    to_mutate = strat.which(field)

    with_strats = []
    for to_mutate_field in to_mutate:
        field_strat = strat.get_field_strat(to_mutate_field)
        if field_strat is not None:
            with_strats.append((to_mutate_field, field_strat))

    # we don't need these ones anymore
    del to_mutate

    # save the current value of all subfields without
    # triggering events
    field._pfp__snapshot(recurse=True)

    count = 0
    for x in six.moves.range(num):

        chosen_fields = set()
        idx_pool = set([x for x in six.moves.xrange(len(with_strats))])

        # modify `at_once` number of fields OR len(with_strats) number of fields,
        # whichever is lower
        for at_onces in six.moves.xrange(min(len(with_strats), at_once)):
            # we'll never pull the same idx from idx_pool more than once
            # since we're removing the idx after choosing it
            rand_idx = rand.sample(idx_pool, 1)[0]
            idx_pool.remove(rand_idx)

            rand_field,field_strat = with_strats[rand_idx]
            chosen_fields.add(rand_field)

            field_strat.mutate(rand_field)

        if yield_changed:
            yield field, chosen_fields
        else:
            # yield back the original field
            yield field

        # restore the saved value of all subfields without
        # triggering events
        field._pfp__restore_snapshot(recurse=True)

Response: Mutate the provided field using the specified strategy.


Instruction:
Can you create a Python 3 function that
returns the strategy identified by its name or class.

Response:
def get_strategy(name_or_cls):
    """Return the strategy identified by its name. If ``name_or_class`` is a class,
    it will be simply returned.
    """
    if isinstance(name_or_cls, six.string_types):
        if name_or_cls not in STRATS:
            raise MutationError("strat is not defined")
        return STRATS[name_or_cls]()

    return name_or_cls()


Instruction:
Create a Python 3 function to
mutate the given field modifying it directly. This is intended to preserve the value of the field.

Response:
def mutate(self, field):
        """Mutate the given field, modifying it directly. This is not
        intended to preserve the value of the field.

        :field: The pfp.fields.Field instance that will receive the new value
        """
        new_val = self.next_val(field)
        field._pfp__set_value(new_val)
        return field


Instruction:
Can you tell what is the following Python 3 function doing
def next_val(self, field):
        import pfp.fuzz.rand as rand

        if self.choices is not None:
            choices = self._resolve_member_val(self.choices, field)
            new_val = rand.choice(choices)
            return self._resolve_val(new_val)

        elif self.prob is not None:
            prob = self._resolve_member_val(self.prob, field)
            rand_val = rand.random()
            curr_total = 0.0
            # iterate through each of the probability choices until
            # we reach one that matches the current rand_val
            for prob_percent, prob_val in prob:
                if rand_val <= curr_total + prob_percent:
                    return self._resolve_val(prob_val)
                curr_total += prob_percent

            raise MutationError("probabilities did not add up to 100%! {}".format(
                [str(x[0]) + " - " + str(x[1])[:10] for x in prob]
            ))

Response: Return a new value to mutate a field with.


Instruction:
How would you explain what the following Python 3 function does
def generate_subid(self, token=None, return_user=False):
    '''generate a new user in the database, still session based so we
       create a new identifier.
    '''
    from expfactory.database.models import Participant
    if not token:
        p = Participant()
    else:
        p = Participant(token=token)
    self.session.add(p)
    self.session.commit()
    if return_user is True:
        return p
    return p.id

Response: generate a new user in the database


Instruction:
Create a Python 3 function to
print a relational database user

Response:
def print_user(self, user):
    '''print a relational database user
    '''
    status = "active"
    token = user.token

    if token in ['finished', 'revoked']:
        status = token

    if token is None:
        token = ''

    subid = "%s\t%s[%s]" %(user.id, token, status)
    print(subid)
    return subid


Instruction:
Can you generate the documentation for the following Python 3 function
def list_users(self, user=None):
    '''list users, each having a model in the database. A headless experiment
       will use protected tokens, and interactive will be based on auto-
       incremented ids.
    '''
    from expfactory.database.models import Participant
    participants = Participant.query.all()
    users = []
    for user in participants:
        users.append(self.print_user(user))
    return users

Response: list users in the database


Instruction:
Implement a function in Python 3 to
generate a new user in the database

Response:
def generate_user(self):
    '''generate a new user in the database, still session based so we
       create a new identifier. This function is called from the users new
       entrypoint, and it assumes we want a user generated with a token.
    '''
    token = str(uuid.uuid4())
    return self.generate_subid(token=token, return_user=True)


Instruction:
Write a Python 3 function for
finishing user will remove a user s token and make the user entry accesible

Response:
def finish_user(self, subid):
    '''finish user will remove a user's token, making the user entry not
       accesible if running in headless model'''

    p = self.revoke_token(subid)
    p.token = "finished"
    self.session.commit()
    return p


Instruction:
Write a Python 3 function for
restarting a user which means revoking and issuing a new token.

Response:
def restart_user(self, subid):
    '''restart a user, which means revoking and issuing a new token.'''
    p = self.revoke_token(subid)
    p = self.refresh_token(subid)
    return p


Instruction:
Implement a function in Python 3 to
retrieve a subject based on a token. Valid means we return a participant invalid means we return None eer

Response:
def validate_token(self, token):
    '''retrieve a subject based on a token. Valid means we return a participant
       invalid means we return None
    '''
    from expfactory.database.models import Participant
    p = Participant.query.filter(Participant.token == token).first()
    if p is not None:
        if p.token.endswith(('finished','revoked')):
            p = None
        else:
            p = p.id
    return p


Instruction:
Here you have a function in Python 3, explain what it does
def revoke_token(self, subid):
    '''revoke a token by removing it. Is done at finish, and also available
    as a command line option'''
    from expfactory.database.models import Participant
    p = Participant.query.filter(Participant.id == subid).first()
    if p is not None:
        p.token = 'revoked'
    self.session.commit()
    return p

Response:
revoke a token by removing it. Is done at finish and also available
    as a command line option


Instruction:
Can you generate a brief explanation for the following Python 3 code
def refresh_token(self, subid):
    '''refresh or generate a new token for a user'''
    from expfactory.database.models import Participant
    p = Participant.query.filter(Participant.id == subid).first()
    if p is not None:
        p.token = str(uuid.uuid4())
    self.session.commit()
    return p

Response: refresh or generate a new token for a user


Instruction:
Explain what the following Python 3 code does
def save_data(self,session, exp_id, content):
    '''save data will obtain the current subid from the session, and save it
       depending on the database type. Currently we just support flat files'''
    from expfactory.database.models import (
        Participant,
        Result
    )
    subid = session.get('subid')
    token = session.get('token')

    self.logger.info('Saving data for subid %s' % subid)

    # We only attempt save if there is a subject id, set at start
    if subid is not None:
        p = Participant.query.filter(Participant.id == subid).first() # better query here

        # Does
        if self.headless and p.token != token:
            self.logger.warning('%s attempting to use mismatched token [%s] skipping save' %(p.id, token))
        elif self.headless and p.token.endswith(('finished','revoked')):
            self.logger.warning('%s attempting to use expired token [%s] skipping save' %(p.id, token))
        else:

            # Preference is to save data under 'data', otherwise do all of it
            if "data" in content:
                content = content['data']

            result = Result(data=content,
                            exp_id=exp_id,
                            participant_id=p.id) # check if changes from str/int

            # Create and save the result
            self.session.add(result)
            p.results.append(result)
            self.session.commit()

            self.logger.info("Save [participant] %s [result] %s" %(p, result))

Response: save data for a specific subject


Instruction:
Make a summary of the following Python 3 code
def init_db(self):
    '''initialize the database, with the default database path or custom with
       a format corresponding to the database type:

       Examples:

       sqlite:////scif/data/expfactory.db
    '''

    # The user can provide a custom string
    if self.database is None:
        self.logger.error("You must provide a database url, exiting.")
        sys.exit(1)

    self.engine = create_engine(self.database, convert_unicode=True)
    self.session = scoped_session(sessionmaker(autocommit=False,
                                               autoflush=False,
                                               bind=self.engine))

    # Database Setup
    Base.query = self.session.query_property()

    # import all modules here that might define models so that
    # they will be registered properly on the metadata.  Otherwise
    # you will have to import them first before calling init_db()
    import expfactory.database.models
    self.Base = Base
    self.Base.metadata.create_all(bind=self.engine)

Response:
initialize the database with the default database path or custom with
       a format corresponding to the database type


Instruction:
How would you implement a function in Python 3 that
wraps the creation of the type so that we can provide a null - stream to initialize it

Response:
def _wrap_type_instantiation(self, type_cls):
        """Wrap the creation of the type so that we can provide
        a null-stream to initialize it"""
        def wrapper(*args, **kwargs):
            # use args for struct arguments??
            return type_cls(stream=self._null_stream)
        return wrapper


Instruction:
Explain what the following Python 3 code does
def level(self):
        res = len(self._scope_stack)
        if self._parent is not None:
            res += self._parent.level()
        return res

Response: Return the current scope level


Instruction:
Write a Python 3 script to
create a new scope and push it on the stack.

Response:
def push(self, new_scope=None):
        """Create a new scope
        :returns: TODO

        """
        if new_scope is None:
            new_scope = {
                "types": {},
                "vars": {}
            }
        self._curr_scope = new_scope
        self._dlog("pushing new scope, scope level = {}".format(self.level()))
        self._scope_stack.append(self._curr_scope)


Instruction:
Can you create a Python 3 function that
returns a new Scope object that has the curr_scope_stack pinned at the current one .

Response:
def clone(self):
        """Return a new Scope object that has the curr_scope
        pinned at the current one
        :returns: A new scope object
        """
        self._dlog("cloning the stack")
        # TODO is this really necessary to create a brand new one?
        # I think it is... need to think about it more.
        # or... are we going to need ref counters and a global
        # scope object that allows a view into (or a snapshot of)
        # a specific scope stack?
        res = Scope(self._log)
        res._scope_stack = self._scope_stack
        res._curr_scope = self._curr_scope
        return res


Instruction:
Create a Python 3 function to
leave the current scope

Response:
def pop(self):
        """Leave the current scope
        :returns: TODO

        """
        res = self._scope_stack.pop()
        self._dlog("popping scope, scope level = {}".format(self.level()))
        self._curr_scope = self._scope_stack[-1]
        return res


Instruction:
Create a Python 3 function to
add a var to the current scope

Response:
def add_var(self, field_name, field, root=False):
        """Add a var to the current scope (vars are fields that
        parse the input stream)

        :field_name: TODO
        :field: TODO
        :returns: TODO

        """
        self._dlog("adding var '{}' (root={})".format(field_name, root))

        # do both so it's not clobbered by intermediate values of the same name
        if root:
            self._scope_stack[0]["vars"][field_name] = field

        # TODO do we allow clobbering of vars???
        self._curr_scope["vars"][field_name] = field


Instruction:
Create a Python 3 function for
returning the first var of name in the current scope stack.

Response:
def get_var(self, name, recurse=True):
        """Return the first var of name ``name`` in the current
        scope stack (remember, vars are the ones that parse the
        input stream)

        :name: The name of the id
        :recurse: Whether parent scopes should also be searched (defaults to True)
        :returns: TODO

        """
        self._dlog("getting var '{}'".format(name))
        return self._search("vars", name, recurse)


Instruction:
Can you write a function in Python 3 where it
adds a local variable in the current scope

Response:
def add_local(self, field_name, field):
        """Add a local variable in the current scope

        :field_name: The field's name
        :field: The field
        :returns: None

        """
        self._dlog("adding local '{}'".format(field_name))
        field._pfp__name = field_name
        # TODO do we allow clobbering of locals???
        self._curr_scope["vars"][field_name] = field


Instruction:
Can you write a function in Python 3 where it
gets the local field from the scope stack. An alias for get_var

Response:
def get_local(self, name, recurse=True):
        """Get the local field (search for it) from the scope stack. An alias
        for ``get_var``

        :name: The name of the local field
        """
        self._dlog("getting local '{}'".format(name))
        return self._search("vars", name, recurse)


Instruction:
Make a summary of the following Python 3 code
def add_type_struct_or_union(self, name, interp, node):
        self.add_type_class(name, StructUnionDef(name, interp, node))

Response: Store the node with the name.


Instruction:
How would you code a function in Python 3 to
record the typedefd name for orig_names and save those.

Response:
def add_type(self, new_name, orig_names):
        """Record the typedefd name for orig_names. Resolve orig_names
        to their core names and save those.

        :new_name: TODO
        :orig_names: TODO
        :returns: TODO

        """
        self._dlog("adding a type '{}'".format(new_name))
        # TODO do we allow clobbering of types???
        res = copy.copy(orig_names)
        resolved_names = self._resolve_name(res[-1])
        if resolved_names is not None:
            res.pop()
            res += resolved_names

        self._curr_scope["types"][new_name] = res


Instruction:
Can you generate a brief explanation for the following Python 3 code
def get_type(self, name, recurse=True):
        self._dlog("getting type '{}'".format(name))
        return self._search("types", name, recurse)

Response: Get the names for the typename created by typedef


Instruction:
How would you explain what the following Python 3 function does
def get_id(self, name, recurse=True):
        self._dlog("getting id '{}'".format(name))
        var = self._search("vars", name, recurse)
        return var

Response:
Get the first id matching name. Will either be a local
        or a var.


Instruction:
Implement a Python 3 function for
searching the scope stack for the specified name in the specified category.

Response:
def _search(self, category, name, recurse=True):
        """Search the scope stack for the name in the specified
        category (types/locals/vars).

        :category: the category to search in (locals/types/vars)
        :name: name to search for
        :returns: None if not found, the result of the found local/type/id
        """
        idx = len(self._scope_stack) - 1
        curr = self._curr_scope
        for scope in reversed(self._scope_stack):
            res = scope[category].get(name, None)
            if res is not None:
                return res

        if recurse and self._parent is not None:
            return self._parent._search(category, name, recurse)

        return None


Instruction:
Can you create a Python 3 function that
adds a native python function func to the interpreter with the given name and return value ret.

Response:
def add_native(cls, name, func, ret, interp=None, send_interp=False):
        """Add the native python function ``func`` into the pfp interpreter with the
        name ``name`` and return value ``ret`` so that it can be called from
        within a template script.

        .. note::
            The :any:`@native <pfp.native.native>` decorator exists to simplify this.

        All native functions must have the signature ``def func(params, ctxt, scope, stream, coord [,interp])``,
        optionally allowing an interpreter param if ``send_interp`` is ``True``.

        Example:

            The example below defines a function ``Sum`` using the ``add_native`` method. ::

                import pfp.fields
                from pfp.fields import PYVAL

                def native_sum(params, ctxt, scope, stream, coord):
                    return PYVAL(params[0]) + PYVAL(params[1])

                pfp.interp.PfpInterp.add_native("Sum", native_sum, pfp.fields.Int64)

        :param basestring name: The name the function will be exposed as in the interpreter.
        :param function func: The native python function that will be referenced.
        :param type(pfp.fields.Field) ret: The field class that the return value should be cast to.
        :param pfp.interp.PfpInterp interp: The specific pfp interpreter the function should be defined in.
        :param bool send_interp: If true, the current pfp interpreter will be added as an argument to the function.
        """
        if interp is None:
            natives = cls._natives
        else:
            # the instance's natives
            natives = interp._natives

        natives[name] = functions.NativeFunction(
            name, func, ret, send_interp
        )


Instruction:
Explain what the following Python 3 code does
def define_natives(cls):
        if len(cls._natives) > 0:
            return

        glob_pattern = os.path.join(os.path.dirname(__file__), "native", "*.py")
        for filename in glob.glob(glob_pattern):
            basename = os.path.basename(filename).replace(".py", "")
            if basename == "__init__":
                continue

            try:
                mod_base = __import__("pfp.native", globals(), locals(), fromlist=[basename])
            except Exception as e:
                sys.stderr.write("cannot import native module {} at '{}'".format(basename, filename))
                raise e
                continue

            mod = getattr(mod_base, basename)
            setattr(mod, "PYVAL", fields.get_value)
            setattr(mod, "PYSTR", fields.get_str)

Response:
Define the native functions for PFP
           .


Instruction:
How would you implement a function in Python 3 that
logs the message to the log

Response:
def _dlog(self, msg, indent_increase=0):
        """log the message to the log"""
        self._log.debug("interp", msg, indent_increase, filename=self._orig_filename, coord=self._coord)


Instruction:
Can you create a Python 3 function that
parses the data stream using the template.

Response:
def parse(self, stream, template, predefines=True, orig_filename=None, keep_successful=False, printf=True):
        """Parse the data stream using the template (e.g. parse the 010 template
        and interpret the template using the stream as the data source).

        :stream: The input data stream
        :template: The template to parse the stream with
        :keep_successful: Return whatever was successfully parsed before an error. ``_pfp__error`` will contain the exception (if one was raised)
        :param bool printf: If ``False``, printfs will be noops (default=``True``)
        :returns: Pfp Dom

        """
        self._dlog("parsing")

        self._printf = printf
        self._orig_filename = orig_filename
        self._stream = stream
        self._template = template
        self._template_lines = self._template.split("\n")
        self._ast = self._parse_string(template, predefines)
        self._dlog("parsed template into ast")

        res = self._run(keep_successful)
        return res


Instruction:
Create a Python 3 function for
evaluating a single statement.

Response:
def eval(self, statement, ctxt=None):
        """Eval a single statement (something returnable)
        """
        self._no_debug = True

        statement = statement.strip()

        if not statement.endswith(";"):
            statement += ";"

        ast = self._parse_string(statement, predefines=False)

        self._dlog("evaluating statement: {}".format(statement))

        try:
            res = None
            for child in ast.children():
                res = self._handle_node(child, self._scope, self._ctxt, self._stream)
            return res
        except errors.InterpReturn as e:
            return e.value
        finally:
            self._no_debug = False


Instruction:
Write a Python 3 script to
set the interpreter should break.

Response:
def set_break(self, break_type):
        """Set if the interpreter should break.

        :returns: TODO
        """
        self._break_type = break_type
        self._break_level = self._scope.level()


Instruction:
How would you implement a function in Python 3 that
returns the current line number in the template and the surrounding source lines as well as the surrounding source lines

Response:
def get_curr_lines(self):
        """Return the current line number in the template,
        as well as the surrounding source lines
        """
        start = max(0, self._coord.line - 5)
        end = min(len(self._template_lines), self._coord.line + 4)

        lines = [(x, self._template_lines[x]) for x in six.moves.range(start, end, 1)]
        return self._coord.line, lines


Instruction:
Can you generate a brief explanation for the following Python 3 code
def set_bitfield_padded(self, val):
        self._padded_bitfield = val
        self._stream.padded = val
        self._ctxt._pfp__padded_bitfield = val

Response: Sets whether the bitfield input or output stream should be padded.


Instruction:
Write a Python 3 function that can
interpret the parsed 010 AST and return the root and set _pfp__error if keep_successfull is True.

Response:
def _run(self, keep_successfull):
        """Interpret the parsed 010 AST
        :returns: PfpDom

        """

        # example self._ast.show():
        #    FileAST:
        #      Decl: data, [], [], []
        #        TypeDecl: data, []
        #          Struct: DATA
        #            Decl: a, [], [], []
        #              TypeDecl: a, []
        #                IdentifierType: ['char']
        #            Decl: b, [], [], []
        #              TypeDecl: b, []
        #                IdentifierType: ['char']
        #            Decl: c, [], [], []
        #              TypeDecl: c, []
        #                IdentifierType: ['char']
        #            Decl: d, [], [], []
        #              TypeDecl: d, []
        #                IdentifierType: ['char']

        self._dlog("interpreting template")

        try:
            # it is important to pass the stream in as the stream
            # may change (e.g. compressed data)
            res = self._handle_node(self._ast, None, None, self._stream)
        except errors.InterpReturn as e:
            # TODO handle exit/return codes (e.g. return -1)
            res = self._root
        except errors.InterpExit as e:
            res = self._root
        except Exception as e:
            if keep_successfull:
                # return the root and set _pfp__error
                res = self._root
                res._pfp__error = e

            else:
                exc_type, exc_obj, traceback = sys.exc_info()
                more_info = "\nException at {}:{}".format(
                    self._orig_filename,
                    self._coord.line
                )
                six.reraise(
                    errors.PfpError,
                    errors.PfpError(exc_obj.__class__.__name__ + ": " + exc_obj.args[0] + more_info if len(exc_obj.args) > 0 else more_info),
                    traceback
                )

        # final drop-in after everything has executed
        if self._break_type != self.BREAK_NONE:
            self.debugger.cmdloop("execution finished")

        types = self.get_types()
        res._pfp__types = types

        return res


Instruction:
Explain what the following Python 3 code does
def _handle_file_ast(self, node, scope, ctxt, stream):
        self._root = ctxt = fields.Dom(stream)
        ctxt._pfp__scope = scope
        self._root._pfp__name = "__root"
        self._root._pfp__interp = self
        self._dlog("handling file AST with {} children".format(len(node.children())))

        for child in node.children():
            self._handle_node(child, scope, ctxt, stream)

        ctxt._pfp__process_fields_metadata()

        return ctxt

Response: Handle the file AST node.


Instruction:
Can you create a Python 3 function that
handles cast nodes :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_cast(self, node, scope, ctxt, stream):
        """Handle cast nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling cast")
        to_type = self._handle_node(node.to_type, scope, ctxt, stream)
        val_to_cast = self._handle_node(node.expr, scope, ctxt, stream)

        res = to_type()
        res._pfp__set_value(val_to_cast)
        return res


Instruction:
How would you implement a function in Python 3 that
handles the typename node.

Response:
def _handle_typename(self, node, scope, ctxt, stream):
        """TODO: Docstring for _handle_typename

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling typename")

        return self._handle_node(node.type, scope, ctxt, stream)


Instruction:
How would you implement a function in Python 3 that
gets the name of the node - check for node. name and node. type. declname. Not why the second one occurs exactly - it occurs with declaring a new struct field with parameters

Response:
def _get_node_name(self, node):
        """Get the name of the node - check for node.name and
        node.type.declname. Not sure why the second one occurs
        exactly - it happens with declaring a new struct field
        with parameters"""
        res = getattr(node, "name", None)
        if res is None:
            return res

        if isinstance(res, AST.TypeDecl):
            return res.declname

        return res


Instruction:
Can you implement a function in Python 3 that
handles a decl node.

Response:
def _handle_decl(self, node, scope, ctxt, stream):
        """TODO: Docstring for _handle_decl.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling decl")

        metadata_processor = None
        if node.metadata is not None:
            #metadata_info = self._handle_metadata(node, scope, ctxt, stream)
            def process_metadata():
                metadata_info = self._handle_metadata(node, scope, ctxt, stream)
                return metadata_info
            metadata_processor = process_metadata

        field_name = self._get_node_name(node)
        field = self._handle_node(node.type, scope, ctxt, stream)
        bitsize = None
        bitfield_rw = None
        if getattr(node, "bitsize", None) is not None:
            bitsize = self._handle_node(node.bitsize, scope, ctxt, stream)
            has_prev = len(ctxt._pfp__children) > 0

            bitfield_rw = None
            if has_prev:
                prev = ctxt._pfp__children[-1]
                # if it was a bitfield as well
                # TODO I don't think this will handle multiple bitfield groups in a row.
                # E.g.
                #     char a: 8, b:8;
                #    char c: 8, d:8;
                if ((self._padded_bitfield and prev.__class__.width == field.width) or not self._padded_bitfield) \
                        and prev.bitsize is not None and prev.bitfield_rw.reserve_bits(bitsize, stream):
                    bitfield_rw = prev.bitfield_rw

            # either because there was no previous bitfield, or the previous was full
            if bitfield_rw is None:
                bitfield_rw = fields.BitfieldRW(self, field)
                bitfield_rw.reserve_bits(bitsize, stream)

        if getattr(node, "is_func_param", False):
            # we want to keep this as a class and not instantiate it
            # instantiation will be done in functions.ParamListDef.instantiate
            field = (field_name, field)

        # locals and consts still get a field instance, but DON'T parse the
        # stream!
        elif "local" in node.quals or "const" in node.quals:
            is_struct = issubclass(field, fields.Struct)
            if not isinstance(field, fields.Field) and not is_struct:
                field = field()
            scope.add_local(field_name, field)

            # this should only be able to be done with locals, right?
            # if not, move it to the bottom of the function
            if node.init is not None:
                val = self._handle_node(node.init, scope, ctxt, stream)
                if is_struct:
                    field = val
                    scope.add_local(field_name, field)
                else:
                    field._pfp__set_value(val)

            if "const" in node.quals:
                field._pfp__freeze()

            field._pfp__interp = self

        elif isinstance(field, functions.Function):
            # eh, just add it as a local...
            # maybe the whole local/vars thinking needs to change...
            # and we should only have ONE map TODO
            field.name = field_name
            scope.add_local(field_name, field)

        elif field_name is not None:
            added_child = False

            # by this point, structs are already instantiated (they need to be
            # in order to set the new context)
            if not isinstance(field, fields.Field):
                if issubclass(field, fields.NumberBase):
                    # use the default bitfield direction
                    if self._bitfield_direction is self.BITFIELD_DIR_DEFAULT:
                        bitfield_left_right = True if field.endian == fields.BIG_ENDIAN else False
                    else:
                        bitfield_left_right = (self._bitfield_direction is self.BITFIELD_DIR_LEFT_RIGHT)

                    field = field(
                        stream,
                        bitsize=bitsize,
                        metadata_processor=metadata_processor,
                        bitfield_rw=bitfield_rw,
                        bitfield_padded=self._padded_bitfield,
                        bitfield_left_right=bitfield_left_right
                    )

                # TODO
                # for now if there's a struct inside of a union that is being
                # parsed when there's an error, the user will lose information
                # about how far the parsing got. Here we are explicitly checking for
                # adding structs and unions to a parent union.
                elif (issubclass(field, fields.Struct) or issubclass(field, fields.Union)) \
                        and not isinstance(ctxt, fields.Union) \
                        and hasattr(field, "_pfp__init"):

                    # this is so that we can have all nested structs added to
                    # the root DOM, even if there's an error in parsing the data.
                    # If we didn't do this, any errors parsing the data would cause
                    # the new struct to not be added to its parent, and the user would
                    # not be able to see how far the script got
                    field = field(stream, metadata_processor=metadata_processor, do_init=False)
                    field._pfp__interp = self
                    field_res = ctxt._pfp__add_child(field_name, field, stream)

                    # when adding a new field to a struct/union/fileast, add it to the
                    # root of the ctxt's scope so that it doesn't get lost by being declared
                    # from within a function
                    scope.add_var(field_name, field_res, root=True)

                    field_res._pfp__interp = self
                    field._pfp__init(stream)
                    added_child = True
                else:
                    field = field(stream, metadata_processor=metadata_processor)

            if not added_child:
                field._pfp__interp = self
                field_res = ctxt._pfp__add_child(field_name, field, stream)
                field_res._pfp__interp = self

                # when adding a new field to a struct/union/fileast, add it to the
                # root of the ctxt's scope so that it doesn't get lost by being declared
                # from within a function
                scope.add_var(field_name, field_res, root=True)

                # this shouldn't be used elsewhere, but should still be explicit with
                # this flag
                added_child = True

        # enums will get here. If there is no name, then no
        # field is being declared (but the enum values _will_
        # get defined). E.g.:
        #     enum <uchar blah {
        #         BLAH1,
        #        BLAH2,
        #        BLAH3
        #     };
        elif field_name is None:
            pass

        return field


Instruction:
How would you code a function in Python 3 to
handle the metadata for the node

Response:
def _handle_metadata(self, node, scope, ctxt, stream):
        """Handle metadata for the node
        """
        self._dlog("handling node metadata {}".format(node.metadata.keyvals))

        keyvals = node.metadata.keyvals

        metadata_info = []

        if "watch" in node.metadata.keyvals or "update" in keyvals:
            metadata_info.append(
                self._handle_watch_metadata(node, scope, ctxt, stream)
            )

        if "packtype" in node.metadata.keyvals or "packer" in keyvals:
            metadata_info.append(
                self._handle_packed_metadata(node, scope, ctxt, stream)
            )

        return metadata_info


Instruction:
Can you tell what is the following Python 3 function doing
def _handle_watch_metadata(self, node, scope, ctxt, stream):
        keyvals = node.metadata.keyvals
        if "watch" not in keyvals:
            raise errors.PfpError("Packed fields require a packer function set")
        if "update" not in keyvals:
            raise errors.PfpError("Packed fields require a packer function set")

        watch_field_name = keyvals["watch"]
        update_func_name = keyvals["update"]

        watch_fields = list(map(lambda x: self.eval(x.strip()), watch_field_name.split(";")))
        update_func = scope.get_id(update_func_name)

        return {
            "type": "watch",
            "watch_fields": watch_fields,
            "update_func": update_func,
            "func_call_info": (ctxt, scope, stream, self, self._coord)
        }

Response: Handle watch vars for fields


Instruction:
Can you tell what is the following Python 3 function doing
def _handle_packed_metadata(self, node, scope, ctxt, stream):
        keyvals = node.metadata.keyvals
        if "packer" not in keyvals and ("pack" not in keyvals or "unpack" not in keyvals):
            raise errors.PfpError("Packed fields require a packer function to be set or pack and unpack functions to be set")
        if "packtype" not in keyvals:
            raise errors.PfpError("Packed fields require a packtype to be set")

        args_ = {}
        if "packer" in keyvals:
            packer_func_name = keyvals["packer"]
            packer_func = scope.get_id(packer_func_name)
            args_["packer"] = packer_func
        elif "pack" in keyvals and "unpack" in keyvals:
            pack_func = scope.get_id(keyvals["pack"])
            unpack_func = scope.get_id(keyvals["unpack"])
            args_["pack"] = pack_func
            args_["unpack"] = unpack_func

        packtype_cls_name = keyvals["packtype"]
        packtype_cls = scope.get_type(packtype_cls_name)
        args_["pack_type"] = packtype_cls

        args_["type"] = "packed"
        args_["func_call_info"] = (ctxt, scope, stream, self, self._coord)
        return args_

Response: Handle packed metadata node.


Instruction:
Make a summary of the following Python 3 code
def _handle_byref_decl(self, node, scope, ctxt, stream):
        self._dlog("handling byref decl")
        field = self._handle_node(node.type.type, scope, ctxt, stream)

        # this will not really be used (maybe except for introspection)
        # with byref function params
        # see issue #35 - we need to wrap the field cls so that the byref
        # doesn't permanently stay on the class
        field = functions.ParamClsWrapper(field)
        field.byref = True
        return field

Response:
TODO: Docstring for _handle_byref_decl.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
Can you generate a brief explanation for the following Python 3 code
def _handle_type_decl(self, node, scope, ctxt, stream):
        self._dlog("handling type decl")
        decl = self._handle_node(node.type, scope, ctxt, stream)
        return decl

Response:
TODO: Docstring for _handle_type_decl.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
Create a Python 3 function to
handle a struct ref node.

Response:
def _handle_struct_ref(self, node, scope, ctxt, stream):
        """TODO: Docstring for _handle_struct_ref.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling struct ref")

        # name
        # field
        struct = self._handle_node(node.name, scope, ctxt, stream)

        try:
            sub_field = getattr(struct, node.field.name)
        except AttributeError as e:
            # should be able to access implicit array items by index OR
            # access the last one's members directly without index
            #
            # E.g.:
            #
            # local int total_length = 0;
            # while(!FEof()) {
            #     HEADER header;
            #   total_length += header.length;
            # }
            if isinstance(struct, fields.Array) and struct.implicit:
                last_item = struct[-1]
                sub_field = getattr(last_item, node.field.name)
            else:
                raise

        return sub_field


Instruction:
Can you generate the documentation for the following Python 3 function
def _handle_init_list(self, node, scope, ctxt, stream):
        self._dlog("handling init list")
        res = []
        for _,init_child in node.children():
            init_field = self._handle_node(init_child, scope, ctxt, stream)
            res.append(init_field)
        return res

Response: Handle the InitList nodes.


Instruction:
Here you have a function in Python 3, explain what it does
def _handle_struct_call_type_decl(self, node, scope, ctxt, stream):
        self._dlog("handling struct with parameters")

        struct_cls = self._handle_node(node.type, scope, ctxt, stream)
        struct_args = self._handle_node(node.args, scope, ctxt, stream)

        res = StructDeclWithParams(scope, struct_cls, struct_args)
        return res

Response: Handle struct type call


Instruction:
Write a Python 3 function that can
handle the struct node.

Response:
def _handle_struct(self, node, scope, ctxt, stream):
        """TODO: Docstring for _handle_struct.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling struct")

        if node.args is not None:
            for param in node.args.params:
                param.is_func_param = True

        # it's actually being defined
        if node.decls is not None:
            struct_cls = StructUnionDef("struct", self, node)

            if node.name is not None:
                scope.add_type_class(node.name, struct_cls)

            return struct_cls

        # it's declaring a struct field. E.g.
        #    struct IFD subDir;
        else:
            return scope.get_type(node.name)


Instruction:
Can you write a function in Python 3 where it
handles the TypeDef and TypeUnion nodes.

Response:
def _handle_typedef(self, node, scope, ctxt, stream):
        """TODO: Docstring for _handle_typedef.

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        is_union_or_struct = (node.type.type.__class__ in [AST.Union, AST.Struct])
        is_enum = (node.type.type.__class__ is AST.Enum)

        if is_union_or_struct:
            self._dlog("handling typedef struct/union '{}'".format(node.name))
            scope.add_type_struct_or_union(node.name, self, node.type.type)
        elif is_enum:
            enum_cls = self._handle_node(node.type, scope, ctxt, stream)
            scope.add_type_class(node.name, enum_cls)
        elif isinstance(node.type, AST.ArrayDecl):
            # this does not parse data, just creates the ArrayDecl class
            array_cls = self._handle_node(node.type, scope, ctxt, stream)
            scope.add_type_class(node.name, array_cls)
        else:
            names = node.type.type.names

            self._dlog("handling typedef '{}' ({})".format(node.name, names))
            # don't actually handle the TypeDecl and Identifier nodes,
            # just directly add the types. Example structure:
            #
            #     Typedef: BLAH, [], ['typedef']
            #        TypeDecl: BLAH, []
            #            IdentifierType: ['unsigned', 'char']
            #
            scope.add_type(node.name, names)


Instruction:
Write a Python 3 script to
convert a string to an integer.

Response:
def _str_to_int(self, string):
        """Check for the hex
        """
        string = string.lower()
        if string.endswith("l"):
            string = string[:-1]
        if string.lower().startswith("0x"):
            # should always match
            match = re.match(r'0[xX]([a-fA-F0-9]+)', string)
            return int(match.group(1), 0x10)
        else:
            return int(string)


Instruction:
Explain what the following Python 3 code does
def _handle_constant(self, node, scope, ctxt, stream):
        self._dlog("handling constant type {}".format(node.type))
        switch = {
            "int": (self._str_to_int, self._choose_const_int_class),
            "long": (self._str_to_int, self._choose_const_int_class),
            # TODO this isn't quite right, but py010parser wouldn't have
            # parsed it if it wasn't correct...
            "float": (lambda x: float(x.lower().replace("f", "")), fields.Float),
            "double": (float, fields.Double),

            # cut out the quotes
            "char": (lambda x: ord(utils.string_escape(x[1:-1])), fields.Char),

            # TODO should this be unicode?? will probably bite me later...
            # cut out the quotes
            "string": (lambda x: str(utils.string_escape(x[1:-1])), fields.String)
        }

        if node.type in switch:
            #return switch[node.type](node.value)
            conversion,field_cls = switch[node.type]
            val = conversion(node.value)

            if hasattr(field_cls, "__call__") and not type(field_cls) is type:
                field_cls = field_cls(val)

            field = field_cls()
            field._pfp__set_value(val)
            return field

        raise UnsupportedConstantType(node.coord, node.type)

Response: Handle a constant node.


Instruction:
Can you tell what is the following Python 3 function doing
def _handle_binary_op(self, node, scope, ctxt, stream):
        self._dlog("handling binary operation {}".format(node.op))
        switch = {
            "+": lambda x,y: x+y,
            "-": lambda x,y: x-y,
            "*": lambda x,y: x*y,
            "/": lambda x,y: x/y,
            "|": lambda x,y: x|y,
            "^": lambda x,y: x^y,
            "&": lambda x,y: x&y,
            "%": lambda x,y: x%y,
            ">": lambda x,y: x>y,
            "<": lambda x,y: x<y,
            "||": lambda x,y: x or y,
            ">=": lambda x,y: x>=y,
            "<=": lambda x,y: x<=y,
            "==": lambda x,y: x == y,
            "!=": lambda x,y: x != y,
            "&&": lambda x,y: x and y,
            ">>": lambda x,y: x >> y,
            "<<": lambda x,y: x << y,
        }

        left_val = self._handle_node(node.left, scope, ctxt, stream)
        right_val = self._handle_node(node.right, scope, ctxt, stream)

        if node.op not in switch:
            raise errors.UnsupportedBinaryOperator(node.coord, node.op)

        res = switch[node.op](left_val, right_val)

        if type(res) is bool:
            new_res = fields.Int()
            if res:
                new_res._pfp__set_value(1)
            else:
                new_res._pfp__set_value(0)
            res = new_res

        return res

Response: Handle binary operator nodes.


Instruction:
Given the following Python 3 function, write the documentation
def _handle_unary_op(self, node, scope, ctxt, stream):
        self._dlog("handling unary op {}".format(node.op))

        special_switch = {
            "parentof"            : self._handle_parentof,
            "exists"            : self._handle_exists,
            "function_exists"    : self._handle_function_exists,
            "p++"                : self._handle_post_plus_plus,
            "p--"                : self._handle_post_minus_minus,
        }

        switch = {
            # for ++i and --i
            "++":        lambda x,v: x.__iadd__(1),
            "--":        lambda x,v: x.__isub__(1),

            "~":        lambda x,v: ~x,
            "!":        lambda x,v: not x,
            "-":        lambda x,v: -x,
            "sizeof":    lambda x,v: (fields.UInt64()+x._pfp__width()),
            "startof":    lambda x,v: (fields.UInt64()+x._pfp__offset),
        }

        if node.op not in switch and node.op not in special_switch:
            raise errors.UnsupportedUnaryOperator(node.coord, node.op)

        if node.op in special_switch:
            return special_switch[node.op](node, scope, ctxt, stream)

        field = self._handle_node(node.expr, scope, ctxt, stream)
        if type(field) is type:
            field = field()
        res = switch[node.op](field, 1)
        if type(res) is bool:
            new_res = field.__class__()
            new_res._pfp__set_value(1 if res == True else 0)
            res = new_res
        return res

Response: Handle unary operator nodes.


Instruction:
How would you implement a function in Python 3 that
handles the parentof unary operator.

Response:
def _handle_parentof(self, node, scope, ctxt, stream):
        """Handle the parentof unary operator

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        # if someone does something like parentof(this).blah,
        # we'll end up with a StructRef instead of an ID ref
        # for node.expr, but we'll also end up with a structref
        # if the user does parentof(a.b.c)...
        #
        # TODO how to differentiate between the two??
        #
        # the proper way would be to do (parentof(a.b.c)).a or
        # (parentof a.b.c).a

        field = self._handle_node(node.expr, scope, ctxt, stream)
        parent = field._pfp__parent
        return parent


Instruction:
Explain what the following Python 3 code does
def _handle_exists(self, node, scope, ctxt, stream):
        res = fields.Int()
        try:
            self._handle_node(node.expr, scope, ctxt, stream)
            res._pfp__set_value(1)
        except AttributeError:
            res._pfp__set_value(0)
        return res

Response: Handle the exists unary operator


Instruction:
Make a summary of the following Python 3 code
def _handle_function_exists(self, node, scope, ctxt, stream):
        res = fields.Int()
        try:
            func = self._handle_node(node.expr, scope, ctxt, stream)
            if isinstance(func, functions.BaseFunction):
                res._pfp__set_value(1)
            else:
                res._pfp__set_value(0)
        except errors.UnresolvedID:
            res._pfp__set_value(0)
        return res

Response: Handle the function_exists unary operator.


Instruction:
Write a Python 3 function that can
handle an ID node.

Response:
def _handle_id(self, node, scope, ctxt, stream):
        """Handle an ID node (return a field object for the ID)

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        if node.name == "__root":
            return self._root
        if node.name == "__this" or node.name == "this":
            return ctxt

        self._dlog("handling id {}".format(node.name))
        field = scope.get_id(node.name)

        is_lazy = getattr(node, "is_lazy", False)

        if field is None and not is_lazy:
            raise errors.UnresolvedID(node.coord, node.name)
        elif is_lazy:
            return LazyField(node.name, scope)

        return field


Instruction:
Can you implement a function in Python 3 that
handles assignment nodes :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_assignment(self, node, scope, ctxt, stream):
        """Handle assignment nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        def add_op(x,y): x += y
        def sub_op(x,y): x -= y
        def div_op(x,y): x /= y
        def mod_op(x,y): x %= y
        def mul_op(x,y): x *= y
        def xor_op(x,y): x ^= y
        def and_op(x,y): x &= y
        def or_op(x,y): x |= y
        def lshift_op(x,y): x <<= y
        def rshift_op(x,y): x >>= y
        def assign_op(x,y): x._pfp__set_value(y)

        switch = {
            "+="    : add_op,
            "-="    : sub_op,
            "/="    : div_op,
            "%="    : mod_op,
            "*="    : mul_op,
            "^="    : xor_op,
            "&="    : and_op,
            "|="    : or_op,
            "<<="    : lshift_op,
            ">>="    : rshift_op,
            "="        : assign_op
        }

        self._dlog("handling assignment")
        field = self._handle_node(node.lvalue, scope, ctxt, stream)
        self._dlog("field = {}".format(field))
        value = self._handle_node(node.rvalue, scope, ctxt, stream)

        if node.op is None:
            self._dlog("value = {}".format(value))
            field._pfp__set_value(value)
        else:
            self._dlog("value {}= {}".format(node.op, value))
            if node.op not in switch:
                raise errors.UnsupportedAssignmentOperator(node.coord, node.op)
            switch[node.op](field, value)


Instruction:
Can you tell what is the following Python 3 function doing
def _handle_func_def(self, node, scope, ctxt, stream):
        self._dlog("handling function definition")
        func = self._handle_node(node.decl, scope, ctxt, stream)
        func.body = node.body

Response:
Handle FuncDef nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
How would you code a function in Python 3 to
handle the ParamList nodes

Response:
def _handle_param_list(self, node, scope, ctxt, stream):
        """Handle ParamList nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling param list")
        # params should be a list of tuples:
        # [(<name>, <field_class>), ...]
        params = []
        for param in node.params:
            self._mark_id_as_lazy(param)
            param_info = self._handle_node(param, scope, ctxt, stream)
            params.append(param_info)

        param_list = functions.ParamListDef(params, node.coord)
        return param_list


Instruction:
Implement a Python 3 function for
handling FuncDecl nodes :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_func_decl(self, node, scope, ctxt, stream):
        """Handle FuncDecl nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling func decl")

        if node.args is not None:
            # could just call _handle_param_list directly...
            for param in node.args.params:
                # see the check in _handle_decl for how this is kept from
                # being added to the local context/scope
                param.is_func_param = True
            params = self._handle_node(node.args, scope, ctxt, stream)
        else:
            params = functions.ParamListDef([], node.coord)

        func_type = self._handle_node(node.type, scope, ctxt, stream)

        func = functions.Function(func_type, params, scope)

        return func


Instruction:
Here you have a function in Python 3, explain what it does
def _handle_func_call(self, node, scope, ctxt, stream):
        self._dlog("handling function call to '{}'".format(node.name.name))
        if node.args is None:
            func_args = []
        else:
            func_args = self._handle_node(node.args, scope, ctxt, stream)
        func = self._handle_node(node.name, scope, ctxt, stream)
        return func.call(func_args, ctxt, scope, stream, self, node.coord)

Response:
Handle FuncCall nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
How would you implement a function in Python 3 that
handles the ExprList nodes

Response:
def _handle_expr_list(self, node, scope, ctxt, stream):
        """Handle ExprList nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling expression list")
        exprs = [
            self._handle_node(expr, scope, ctxt, stream) for expr in node.exprs
        ]
        return exprs


Instruction:
How would you implement a function in Python 3 that
handles the compound nodes

Response:
def _handle_compound(self, node, scope, ctxt, stream):
        """Handle Compound nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling compound statement")
        #scope.push()

        try:
            for child in node.children():
                self._handle_node(child, scope, ctxt, stream)

        # in case a return occurs, be sure to pop the scope
        # (returns are implemented by raising an exception)
        finally:
            #scope.pop()
            pass


Instruction:
Write a Python 3 function for
handling Return nodes :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_return(self, node, scope, ctxt, stream):
        """Handle Return nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling return")
        if node.expr is None:
            ret_val = None
        else:
            ret_val = self._handle_node(node.expr, scope, ctxt, stream)
        self._dlog("return value = {}".format(ret_val))
        raise errors.InterpReturn(ret_val)


Instruction:
How would you explain what the following Python 3 function does
def _handle_enum(self, node, scope, ctxt, stream):
        self._dlog("handling enum")
        if node.type is None:
            enum_cls = fields.Int
        else:
            enum_cls = self._handle_node(node.type, scope, ctxt, stream)

        enum_vals = {}
        curr_val = enum_cls()
        curr_val._pfp__value = -1
        for enumerator in node.values.enumerators:
            if enumerator.value is not None:
                curr_val = self._handle_node(enumerator.value, scope, ctxt, stream)
            else:
                curr_val = curr_val + 1
            curr_val._pfp__freeze()
            enum_vals[enumerator.name] = curr_val
            enum_vals[fields.PYVAL(curr_val)] = enumerator.name
            scope.add_local(enumerator.name, curr_val)

        if node.name is not None:
            enum_cls = EnumDef(node.name, enum_cls, enum_vals)
            scope.add_type_class(node.name, enum_cls)

        else:
            enum_cls = EnumDef("enum_" + enum_cls.__name__, enum_cls, enum_vals)
            # don't add to scope if we don't have a name

        return enum_cls

Response: Handles the Enum nodes


Instruction:
Make a summary of the following Python 3 code
def _handle_array_decl(self, node, scope, ctxt, stream):
        self._dlog("handling array declaration '{}'".format(node.type.declname))

        if node.dim is None:
            # will be used
            array_size = None
        else:
            array_size = self._handle_node(node.dim, scope, ctxt, stream)
        self._dlog("array size = {}".format(array_size))
        # TODO node.dim_quals
        # node.type
        field_cls = self._handle_node(node.type, scope, ctxt, stream)
        self._dlog("field class = {}".format(field_cls))
        array = ArrayDecl(field_cls, array_size)
        #array = fields.Array(array_size, field_cls)
        array._pfp__name = node.type.declname
        #array._pfp__parse(stream)
        return array

Response:
Handle ArrayDecl nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
Make a summary of the following Python 3 code
def _handle_array_ref(self, node, scope, ctxt, stream):
        ary = self._handle_node(node.name, scope, ctxt, stream)
        subscript = self._handle_node(node.subscript, scope, ctxt, stream)
        return ary[fields.PYVAL(subscript)]

Response:
Handle ArrayRef nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
Given the following Python 3 function, write the documentation
def _handle_if(self, node, scope, ctxt, stream):
        self._dlog("handling if/ternary_op")
        cond = self._handle_node(node.cond, scope, ctxt, stream)
        if cond:
            # there should always be an iftrue
            return self._handle_node(node.iftrue, scope, ctxt, stream)
        else:
            if node.iffalse is not None:
                return self._handle_node(node.iffalse, scope, ctxt, stream)

Response:
Handle If nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO


Instruction:
Create a Python 3 function to
handle For nodes :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_for(self, node, scope, ctxt, stream):
        """Handle For nodes

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling for")
        if node.init is not None:
            # perform the init
            self._handle_node(node.init, scope, ctxt, stream)

        while node.cond is None or self._handle_node(node.cond, scope, ctxt, stream):
            if node.stmt is not None:
                try:
                    # do the for body
                    self._handle_node(node.stmt, scope, ctxt, stream)
                except errors.InterpBreak as e:
                    break

                # we still need to interpret the "next" statement,
                # so just pass
                except errors.InterpContinue as e:
                    pass

            if node.next is not None:
                # do the next statement
                self._handle_node(node.next, scope, ctxt, stream)


Instruction:
Create a Python 3 function to
handle a while node.

Response:
def _handle_while(self, node, scope, ctxt, stream):
        """Handle break node

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling while")
        while node.cond is None or self._handle_node(node.cond, scope, ctxt, stream):
            if node.stmt is not None:
                try:
                    self._handle_node(node.stmt, scope, ctxt, stream)
                except errors.InterpBreak as e:
                    break
                except errors.InterpContinue as e:
                    pass


Instruction:
Implement a Python 3 function for
handling break node :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_switch(self, node, scope, ctxt, stream):
        """Handle break node

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        def exec_case(idx, cases):
            # keep executing cases until a break is found,
            # or they've all been executed
            for case in cases[idx:]:
                stmts = case.stmts
                try:
                    for stmt in stmts:
                        self._handle_node(stmt, scope, ctxt, stream)
                except errors.InterpBreak as e:
                    break

        def get_stmts(stmts, res=None):
            if res is None:
                res = []

            stmts = self._flatten_list(stmts)
            for stmt in stmts:
                if isinstance(stmt, tuple):
                    stmt = stmt[1]

                res.append(stmt)

                if stmt.__class__ in [AST.Case, AST.Default]:
                    get_stmts(stmt.stmts, res)

            return res

        def get_cases(nodes, acc=None):
            cases = []

            stmts = get_stmts(nodes)
            for stmt in stmts:
                if stmt.__class__ in [AST.Case, AST.Default]:
                    cases.append(stmt)
                    stmt.stmts = []
                else:
                    cases[-1].stmts.append(stmt)

            return cases

        cond = self._handle_node(node.cond, scope, ctxt, stream)

        default_idx = None
        found_match = False

        cases = getattr(node, "pfp_cases", None)
        if cases is None:
            cases = get_cases(node.stmt.children())
            node.pfp_cases = cases

        for idx,child in enumerate(cases):
            if child.__class__ == AST.Default:
                default_idx = idx
                continue
            elif child.__class__ == AST.Case:
                expr = self._handle_node(child.expr, scope, ctxt, stream)
                if expr == cond:
                    found_match = True
                    exec_case(idx, cases)
                    break

        if default_idx is not None and not found_match:
            exec_case(default_idx, cases)


Instruction:
Can you tell what is the following Python 3 function doing
def _handle_break(self, node, scope, ctxt, stream):
        self._dlog("handling break")
        raise errors.InterpBreak()

Response: Handle a break node


Instruction:
Create a Python 3 function to
handle continue node :node: TODO :scope: TODO :ctxt: TODO :stream: TODO :returns: TODO

Response:
def _handle_continue(self, node, scope, ctxt, stream):
        """Handle continue node

        :node: TODO
        :scope: TODO
        :ctxt: TODO
        :stream: TODO
        :returns: TODO

        """
        self._dlog("handling continue")
        raise errors.InterpContinue()


Instruction:
How would you explain what the following Python 3 function does
def _handle_decl_list(self, node, scope, ctxt, stream):
        self._dlog("handling decl list")
        # just handle each declaration
        for decl in node.decls:
            self._handle_node(decl, scope, ctxt, stream)

Response: Handle declarations in a list node


Instruction:
Can you write a function in Python 3 where it
creates a new scope object for the current natives and log.

Response:
def _create_scope(self):
        """TODO: Docstring for _create_scope.
        :returns: TODO

        """
        res = Scope(self._log)

        for func_name,native_func in six.iteritems(self._natives):
            res.add_local(func_name, native_func)

        return res


Instruction:
Write a Python 3 script for
returning the value of the node. It is expected to be either an AST. ID instance or a constant .

Response:
def _get_value(self, node, scope, ctxt, stream):
        """Return the value of the node. It is expected to be
        either an AST.ID instance or a constant

        :node: TODO
        :returns: TODO

        """

        res = self._handle_node(node, scope, ctxt, stream)

        if isinstance(res, fields.Field):
            return res._pfp__value

        # assume it's a constant
        else:
            return res


Instruction:
Can you implement a function in Python 3 that
resolves the names to a class in fields. py

Response:
def _resolve_to_field_class(self, names, scope):
        """Resolve the names to a class in fields.py, resolving past
        typedefs, etc

        :names: TODO
        :scope: TODO
        :ctxt: TODO
        :returns: TODO

        """
        switch = {
            "char"    : "Char",
            "int"     : "Int",
            "long"    : "Int",
            "int64"   : "Int64",
            "uint64"  : "UInt64",
            "short"   : "Short",
            "double"  : "Double",
            "float"   : "Float",
            "void"    : "Void",
            "string"  : "String",
            "wstring" : "WString"
        }

        core = names[-1]

        if core not in switch:
            # will return a list of resolved names
            type_info = scope.get_type(core)
            if type(type_info) is type and issubclass(type_info, fields.Field):
                return type_info
            resolved_names = type_info
            if resolved_names is None:
                raise errors.UnresolvedType(self._coord, " ".join(names), " ")
            if resolved_names[-1] not in switch:
                raise errors.UnresolvedType(self._coord, " ".join(names), " ".join(resolved_names))
            names = copy.copy(names)
            names.pop()
            names += resolved_names

        if len(names) >= 2 and names[-1] == names[-2] and names[-1] == "long":
            res = "Int64"
        else:
            res = switch[names[-1]]

        if names[-1] in ["char", "short", "int", "long"] and "unsigned" in names[:-1]:
            res = "U" + res

        cls = getattr(fields, res)
        return cls


Instruction:
How would you code a function in Python 3 to
convert the bit list into bytes.

Response:
def bits_to_bytes(bits):
    """Convert the bit list into bytes. (Assumes bits is a list
    whose length is a multiple of 8)
    """
    if len(bits) % 8 != 0:
        raise Exception("num bits must be multiple of 8")

    res = ""

    for x in six.moves.range(0, len(bits), 8):
        byte_bits = bits[x:x+8]
        byte_val = int(''.join(map(str, byte_bits)), 2)
        res += chr(byte_val)

    return utils.binary(res)


Instruction:
Implement a function in Python 3 to
convert a list of bytes to a list of bits

Response:
def bytes_to_bits(bytes_):
    """Convert bytes to a list of bits
    """
    res = []
    for x in bytes_:
        if not isinstance(x, int):
            x = ord(x)
        res += byte_to_bits(x)
    return res


Instruction:
Implement a function in Python 3 to
return True if the stream has reached EOF or False otherwise.

Response:
def is_eof(self):
        """Return if the stream has reached EOF or not
        without discarding any unflushed bits

        :returns: True/False
        """
        pos = self._stream.tell()
        byte = self._stream.read(1)
        self._stream.seek(pos, 0)

        return utils.binary(byte) == utils.binary("")


Instruction:
Can you tell what is the following Python 3 function doing
def read(self, num):
        start_pos = self.tell()

        if self.padded:
            # we toss out any uneven bytes
            self._bits.clear()
            res = utils.binary(self._stream.read(num))
        else:
            bits = self.read_bits(num * 8)
            res = bits_to_bytes(bits)
            res = utils.binary(res)

        end_pos = self.tell()
        self._update_consumed_ranges(start_pos, end_pos)

        return res

Response: Reads num number of bytes from the stream.


Instruction:
Given the following Python 3 function, write the documentation
def read_bits(self, num):
        if num > len(self._bits):
            needed = num - len(self._bits)
            num_bytes = int(math.ceil(needed / 8.0))
            read_bytes = self._stream.read(num_bytes)

            for bit in bytes_to_bits(read_bytes):
                self._bits.append(bit)

        res = []
        while len(res) < num and len(self._bits) > 0:
            res.append(self._bits.popleft())

        return res

Response: Read num number of bits from the stream and return them as a list.


Instruction:
Write a Python 3 script to
write the data to the stream.

Response:
def write(self, data):
        """Write data to the stream

        :data: the data to write to the stream
        :returns: None
        """
        if self.padded:
            # flush out any remaining bits first
            if len(self._bits) > 0:
                self._flush_bits_to_stream()
            self._stream.write(data)
        else:
            # nothing to do here
            if len(data) == 0:
                return

            bits = bytes_to_bits(data)
            self.write_bits(bits)


Instruction:
Given the following Python 3 function, write the documentation
def write_bits(self, bits):
        for bit in bits:
            self._bits.append(bit)

        while len(self._bits) >= 8:
            byte_bits = [self._bits.popleft() for x in six.moves.range(8)]
            byte = bits_to_bytes(byte_bits)
            self._stream.write(byte)

Response: Write the bits to the stream.


Instruction:
How would you explain what the following Python 3 function does
def tell(self):
        res = self._stream.tell()
        if len(self._bits) > 0:
            res -= 1
        return res

Response: Return the current position in the stream


Instruction:
Can you tell what is the following Python 3 function doing
def seek(self, pos, seek_type=0):
        self._bits.clear()
        return self._stream.seek(pos, seek_type)

Response: Seek to the specified position in the stream with seek_type.


Instruction:
Given the following Python 3 function, write the documentation
def size(self):
        pos = self._stream.tell()
        # seek to the end of the stream
        self._stream.seek(0,2)
        size = self._stream.tell()
        self._stream.seek(pos, 0)

        return size

Response: Return the size of the resource store in bytes or - 1 if it cannot be determined.


Instruction:
How would you explain what the following Python 3 function does
def unconsumed_ranges(self):
        res = IntervalTree()

        prev = None

        # normal iteration is not in a predictable order
        ranges = sorted([x for x in self.range_set], key=lambda x: x.begin)

        for rng in ranges:
            if prev is None:
                prev = rng
                continue
            res.add(Interval(prev.end, rng.begin))
            prev = rng

        # means we've seeked past the end
        if len(self.range_set[self.tell()]) != 1:
            res.add(Interval(prev.end, self.tell()))

        return res

Response:
Return an IntervalTree of unconsumed ranges of the format
        start end with the end value being included


Instruction:
Can you implement a function in Python 3 that
updates the self. consumed_ranges array with which byte ranges have been consecutively consumed.

Response:
def _update_consumed_ranges(self, start_pos, end_pos):
        """Update the ``self.consumed_ranges`` array with which
        byte ranges have been consecutively consumed.
        """
        self.range_set.add(Interval(start_pos, end_pos+1))
        self.range_set.merge_overlaps()


Instruction:
Implement a Python 3 function for
flushing the bits to the stream. This is used when the bits are not written to the stream.

Response:
def _flush_bits_to_stream(self):
        """Flush the bits to the stream. This is used when
        a few bits have been read and ``self._bits`` contains unconsumed/
        flushed bits when data is to be written to the stream
        """
        if len(self._bits) == 0:
            return 0

        bits = list(self._bits)

        diff = 8 - (len(bits) % 8)
        padding = [0] * diff

        bits = bits + padding

        self._stream.write(bits_to_bytes(bits))

        self._bits.clear()


Instruction:
Explain what the following Python 3 code does
def _validate_markdown(self, expfile):
        '''ensure that fields are present in markdown file'''

        try:
            import yaml
        except:
            bot.error('Python yaml is required for testing yml/markdown files.')
            sys.exit(1)

        self.metadata = {}
        uid = os.path.basename(expfile).strip('.md')

        if os.path.exists(expfile):
            with open(expfile, "r") as stream:
                docs = yaml.load_all(stream)
                for doc in docs:
                    if isinstance(doc,dict):
                        for k,v in doc.items():
                            print('%s: %s' %(k,v))
                            self.metadata[k] = v
            self.metadata['uid'] = uid

            fields = ['github', 'preview', 'name', 'layout',
                      'tags', 'uid', 'maintainer']

            # Tests for all fields
            for field in fields:
                if field not in self.metadata:
                    return False
                if self.metadata[field] in ['',None]:
                    return False

            if 'github' not in self.metadata['github']:
                return notvalid('%s: not a valid github repository' % name)
            if not isinstance(self.metadata['tags'],list):
                return notvalid('%s: tags must be a list' % name)
            if not re.search("(\w+://)(.+@)*([\w\d\.]+)(:[\d]+){0,1}/*(.*)", self.metadata['github']):
                return notvalid('%s is not a valid URL.' %(self.metadata['github']))

        return True

Response: ensure that all fields in the given file are present in the given file


Instruction:
Write a Python 3 function that can
perform all checks for required variables before returning to

Response:
def perform_checks(template,
                   do_redirect=False,
                   context=None,
                   next=None,
                   quiet=False):

    '''return all checks for required variables before returning to
       desired view

       Parameters
       ==========
       template: the html template to render
       do_redirect: if True, perform a redirect and not render
       context: dictionary of context variables to pass to render_template
       next: a pre-defined next experiment, will calculate if None
       quiet: decrease verbosity

    '''
    from expfactory.server import app
    username = session.get('username')
    subid = session.get('subid')

    # If redirect, "last" is currently active (about to start)
    # If render, "last" is last completed / active experiment (just finished)
    last = session.get('exp_id')
    if next is None:
        next = app.get_next(session)
    session['exp_id'] = next

    # Headless mode requires token
    if "token" not in session and app.headless is True:
        flash('A token is required for these experiments.')
        return redirect('/')

    # Update the user / log
    if quiet is False:
        app.logger.info("[router] %s --> %s [subid] %s [user] %s" %(last,
                                                                    next,
                                                                    subid,
                                                                    username))

    if username is None and app.headless is False:
        flash('You must start a session before doing experiments.')
        return redirect('/')

    if subid is None:
        flash('You must have a participant identifier before doing experiments')
        return redirect('/')

    if next is None:
        flash('Congratulations, you have finished the battery!')
        return redirect('/finish')

    if do_redirect is True:
        app.logger.debug('Redirecting to %s' %template)
        return redirect(template)

    if context is not None and isinstance(context, dict):
        app.logger.debug('Rendering %s' %template)
        return render_template(template, **context)
    return render_template(template)


Instruction:
Make a summary of the following Python 3 code
def FSeek(params, ctxt, scope, stream, coord):
    if len(params) != 1:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "FSeek accepts only one argument")

    pos = PYVAL(params[0])
    curr_pos = stream.tell()

    fsize = stream.size()

    if pos > fsize:
        stream.seek(fsize)
        return -1
    elif pos < 0:
        stream.seek(0)
        return -1

    diff = pos - curr_pos
    if diff < 0:
        stream.seek(pos)
        return 0

    data = stream.read(diff)

    # let the ctxt automatically append numbers, as needed, unless the previous
    # child was also a skipped field
    skipped_name = "_skipped"

    if len(ctxt._pfp__children) > 0 and ctxt._pfp__children[-1]._pfp__name.startswith("_skipped"):
        old_name = ctxt._pfp__children[-1]._pfp__name
        data = ctxt._pfp__children[-1].raw_data + data
        skipped_name = old_name
        ctxt._pfp__children = ctxt._pfp__children[:-1]
        del ctxt._pfp__children_map[old_name]

    tmp_stream = bitwrap.BitwrappedStream(six.BytesIO(data))
    new_field = pfp.fields.Array(len(data), pfp.fields.Char, tmp_stream)
    ctxt._pfp__add_child(skipped_name, new_field, stream)
    scope.add_var(skipped_name, new_field)

    return 0

Response: Returns 0 if successful or - 1 if unsuccessful.


Instruction:
Here you have a function in Python 3, explain what it does
def FSkip(params, ctxt, scope, stream, coord):
    if len(params) != 1:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "FSkip accepts only one argument")

    skip_amt = PYVAL(params[0])
    pos = skip_amt + stream.tell()
    return FSeek([pos], ctxt, scope, stream, coord)

Response: Returns 0 if successful or - 1 if unsuccessful.


Instruction:
Can you tell what is the following Python 3 function doing
def packer_gzip(params, ctxt, scope, stream, coord):
    if len(params) <= 1:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "at least two arguments")

    # to gzip it (pack it)
    if params[0]:
        return pack_gzip(params[1:], ctxt, scope, stream, coord)
    else:
        return unpack_gzip(params[1:], ctxt, scope, stream, coord)

Response: Packs and unpacks the data of the current node into a new node.


Instruction:
Explain what the following Python 3 code does
def pack_gzip(params, ctxt, scope, stream, coord):
    if len(params) == 0:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "at least one argument")

    built = utils.binary("")
    for param in params:
        if isinstance(param, pfp.fields.Field):
            built += param._pfp__build()
        else:
            built += param

    return zlib.compress(built)

Response: Packs the params and returns a gzipped version of the resulting data.


Instruction:
Implement a function in Python 3 to
watch the total length of each parameter.

Response:
def watch_length(params, ctxt, scope, stream, coord):
    """WatchLength - Watch the total length of each of the params.

    Example:
        The code below uses the ``WatchLength`` update function to update
        the ``length`` field to the length of the ``data`` field ::

            int length<watch=data, update=WatchLength>;
            char data[length];
    """
    if len(params) <= 1:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "at least two arguments")

    to_update = params[0]

    total_size = 0
    for param in params[1:]:
        total_size += param._pfp__width()

    to_update._pfp__set_value(total_size)


Instruction:
Implement a function in Python 3 to
watch the total CRC32 of the params.

Response:
def watch_crc(params, ctxt, scope, stream, coord):
    """WatchCrc32 - Watch the total crc32 of the params.

    Example:
        The code below uses the ``WatchCrc32`` update function to update
        the ``crc`` field to the crc of the ``length`` and ``data`` fields ::

            char length;
            char data[length];
            int crc<watch=length;data, update=WatchCrc32>;
    """
    if len(params) <= 1:
        raise errors.InvalidArguments(coord, "{} args".format(len(params)), "at least two arguments")

    to_update = params[0]

    total_data = utils.binary("")
    for param in params[1:]:
        total_data += param._pfp__build()

    to_update._pfp__set_value(binascii.crc32(total_data))


Instruction:
Can you write a function in Python 3 where it
validates folder takes a cloned github repo ensures the existence of the config. json and validates it.

Response:
def _validate_folder(self, folder=None):
        ''' validate folder takes a cloned github repo, ensures
            the existence of the config.json, and validates it.
        '''
        from expfactory.experiment import load_experiment

        if folder is None:
            folder=os.path.abspath(os.getcwd())

        config = load_experiment(folder, return_path=True)

        if not config:
            return notvalid("%s is not an experiment." %(folder))

        return self._validate_config(folder)


Instruction:
Here you have a function in Python 3, explain what it does
def validate(self, folder, cleanup=False, validate_folder=True):
        ''' validate is the entrypoint to all validation, for
            a folder, config, or url. If a URL is found, it is
            cloned and cleaned up.
           :param validate_folder: ensures the folder name (github repo)
                                   matches.
        '''

        # Obtain any repository URL provided
        if folder.startswith('http') or 'github' in folder:
            folder = clone(folder, tmpdir=self.tmpdir)

        # Load config.json if provided directly
        elif os.path.basename(folder) == 'config.json':
            config = os.path.dirname(folder)
            return self._validate_config(config, validate_folder)

        # Otherwise, validate folder and cleanup
        valid = self._validate_folder(folder)
        if cleanup is True:
            shutil.rmtree(folder)
        return valid

Response: Validate a folder and optionally a config. json or url.


Instruction:
Can you write a function in Python 3 where it
validates config is the primary validation function that checks for presence and format of required fields. Parameters ========== :folder: full path to folder with config.json :name: if provided, the folder name to check against exp_id

Response:
def _validate_config(self, folder, validate_folder=True):
        ''' validate config is the primary validation function that checks
            for presence and format of required fields.

        Parameters
        ==========
        :folder: full path to folder with config.json
        :name: if provided, the folder name to check against exp_id
        '''
        config = "%s/config.json" % folder
        name = os.path.basename(folder)
        if not os.path.exists(config):
            return notvalid("%s: config.json not found." %(folder))

        # Load the config
        try:
            config = read_json(config)
        except:
            return notvalid("%s: cannot load json, invalid." %(name))

        # Config.json should be single dict
        if isinstance(config, list):
            return notvalid("%s: config.json is a list, not valid." %(name))

        # Check over required fields
        fields = self.get_validation_fields()
        for field,value,ftype in fields:

            bot.verbose('field: %s, required: %s' %(field,value))

            # Field must be in the keys if required
            if field not in config.keys():
                if value == 1:
                    return notvalid("%s: config.json is missing required field %s" %(name,field))

            # Field is present, check type
            else:
                if not isinstance(config[field], ftype):
                    return notvalid("%s: invalid type, must be %s." %(name,str(ftype)))

            # Expid gets special treatment
            if field == "exp_id" and validate_folder is True:
                if config[field] != name:
                    return notvalid("%s: exp_id parameter %s does not match folder name."
                                    %(name,config[field]))

                # name cannot have special characters, only _ and letters/numbers
                if not re.match("^[a-z0-9_-]*$", config[field]):
                    message = "%s: exp_id parameter %s has invalid characters"
                    message += "only lowercase [a-z],[0-9], -, and _ allowed."
                    return notvalid(message %(name,config[field]))

        return True


Instruction:
Can you generate a brief explanation for the following Python 3 code
def get_validation_fields(self):
        '''get_validation_fields returns a list of tuples (each a field)
           we only require the exp_id to coincide with the folder name, for the sake
           of reproducibility (given that all are served from sample image or Github
           organization). All other fields are optional.
           To specify runtime variables, add to "experiment_variables"

                 0: not required, no warning
                 1: required, not valid
                 2: not required, warning
                type: indicates the variable type
        '''
        return [("name",1,str),   # required
                ("time",1,int),
                ("url",1,str),
                ("description",1, str),
                ("instructions",1, str),
                ("exp_id",1,str),

                ("install",0, list),  # list of commands to install / build experiment
                ("contributors",0, list), # not required
                ("reference",0, list),
                ("cognitive_atlas_task_id",0,str),
                ("template",0,str)]

Response: get_validation_fields returns a list of tuples that are required to be passed to the validation function.


Instruction:
Here you have a function in Python 3, explain what it does
def generate_runtime_vars(variable_file=None, sep=','):
    '''generate a lookup data structure from a
       delimited file. We typically obtain the file name and delimiter from
       the environment by way of EXPFACTORY_RUNTIME_VARS, and
       EXPFACTORY_RUNTIME_DELIM, respectively, but the user can also parse
       from a custom variable file by way of specifying it to the function
       (preference is given here). The file should be csv, with the
       only required first header field as "token" and second as "exp_id" to
       distinguish the participant ID and experiment id. The subsequent
       columns should correspond to experiment variable names. No special parsing
       of either is done.

       Parameters
       ==========
       variable_file: full path to the tabular file with token, exp_id, etc.
       sep: the default delimiter to use, if not set in enironment.

       Returns
       =======
       varset: a dictionary lookup by exp_id and then participant ID.

       { 'test-parse-url': {
                             '123': {
                                      'color': 'red',
                                      'globalname': 'globalvalue',
                                      'words': 'at the thing'
                                    },

                             '456': {'color': 'blue',
                                     'globalname': 'globalvalue',
                                     'words': 'omg tacos'}
                              }
       }

    '''

    # First preference goes to runtime, then environment, then unset

    if variable_file is None:
        if EXPFACTORY_RUNTIME_VARS is not None:
            variable_file = EXPFACTORY_RUNTIME_VARS

    if variable_file is not None:
        if not os.path.exists(variable_file):
            bot.warning('%s is set, but not found' %variable_file)
            return variable_file

    # If still None, no file
    if variable_file is None:
        return variable_file

    # If we get here, we have a variable file that exists
    delim = sep
    if EXPFACTORY_RUNTIME_DELIM is not None:
        delim = EXPFACTORY_RUNTIME_DELIM
    bot.debug('Delim for variables file set to %s' %sep)

    # Read in the file, generate config

    varset = dict()
    rows = _read_runtime_vars(variable_file)

    if len(rows) > 0:

        # When we get here, we are sure to have
        # 'exp_id', 'var_name', 'var_value', 'token'

        for row in rows:

            exp_id = row[0].lower()   # exp-id must be lowercase
            var_name = row[1]
            var_value = row[2]
            token = row[3]

            # Level 1: Experiment ID
            if exp_id not in varset:
                varset[exp_id] = {}

            # Level 2: Participant ID
            if token not in varset[exp_id]:
                varset[exp_id][token] = {}

            # If found global setting, courtesy debug message
            if token == "*":
                bot.debug('Found global variable %s' %var_name)

            # Level 3: is the variable, issue warning if already defined
            if var_name in varset[exp_id][token]:
                bot.warning('%s defined twice %s:%s' %(var_name, exp_id, token))
            varset[exp_id][token][var_name] = var_value

    return varset

Response: generate a lookup data structure from a delimited file.


Instruction:
Write a Python 3 script to
read the entire runtime variable file and return a list of lists each corresponding to a row.

Response:
def _read_runtime_vars(variable_file, sep=','):
    '''read the entire runtime variable file, and return a list of lists,
       each corresponding to a row. We also check the header, and exit
       if anything is missing or malformed.

       Parameters
       ==========

       variable_file: full path to the tabular file with token, exp_id, etc.
       sep: the default delimiter to use, if not set in enironment.

       Returns
       =======

       valid_rows: a list of lists, each a valid row

           [['test-parse-url', 'globalname', 'globalvalue', '*'],
            ['test-parse-url', 'color', 'red', '123'],
            ['test-parse-url', 'color', 'blue', '456'],
            ['test-parse-url', 'words', 'at the thing', '123'],
            ['test-parse-url', 'words', 'omg tacos', '456']]

    '''

    rows = [x for x in read_file(variable_file).split('\n') if x.strip()]
    valid_rows = []

    if len(rows) > 0:

        # Validate header and rows, exit if not valid

        header = rows.pop(0).split(sep)
        validate_header(header)
        for row in rows:
            row = _validate_row(row, sep=sep, required_length=4)

            # If the row is returned, it is valid

            if row:
                valid_rows.append(row)

    return valid_rows


Instruction:
Implement a Python 3 function for
parsing a row into a list of strings

Response:
def _parse_row(row, sep=','):
    '''parse row is a helper function to simply clean up a string, and parse
       into a row based on a delimiter. If a required length is provided,
       we check for this too.

    '''
    parsed = row.split(sep)
    parsed = [x for x in parsed if x.strip()]
    return parsed


Instruction:
Can you generate the documentation for the following Python 3 function
def validate_header(header, required_fields=None):
    '''validate_header ensures that the first row contains the exp_id,
       var_name, var_value, and token. Capitalization isn't important, but
       ordering is. This criteria is very strict, but it's reasonable
       to require.

       Parameters
       ==========
       header: the header row, as a list
       required_fields: a list of required fields. We derive the required
                        length from this list.

       Does not return, instead exits if malformed. Runs silently if OK.

    '''
    if required_fields is None:
        required_fields = ['exp_id', 'var_name', 'var_value', 'token']

    # The required length of the header based on required fields

    length = len(required_fields)

    # This is very strict, but no reason not to be

    header = _validate_row(header, required_length=length)
    header = [x.lower() for x in header]

    for idx in range(length):
        field = header[idx].lower().strip()
        if required_fields[idx] != field:
            bot.error('Malformed header field %s, exiting.' %field)
            sys.exit(1)

Response: validate_header verifies that the header row contains the exp_id var_name var_value and token.


Instruction:
How would you code a function in Python 3 to
compile the pattern lines.

Response:
def from_lines(cls, pattern_factory, lines):
		"""
		Compiles the pattern lines.

		*pattern_factory* can be either the name of a registered pattern
		factory (:class:`str`), or a :class:`~collections.abc.Callable` used
		to compile patterns. It must accept an uncompiled pattern (:class:`str`)
		and return the compiled pattern (:class:`.Pattern`).

		*lines* (:class:`~collections.abc.Iterable`) yields each uncompiled
		pattern (:class:`str`). This simply has to yield each line so it can
		be a :class:`file` (e.g., from :func:`open` or :class:`io.StringIO`)
		or the result from :meth:`str.splitlines`.

		Returns the :class:`PathSpec` instance.
		"""
		if isinstance(pattern_factory, string_types):
			pattern_factory = util.lookup_pattern(pattern_factory)
		if not callable(pattern_factory):
			raise TypeError("pattern_factory:{!r} is not callable.".format(pattern_factory))

		if isinstance(lines, (bytes, unicode)):
			raise TypeError("lines:{!r} is not an iterable.".format(lines))

		lines = [pattern_factory(line) for line in lines if line]
		return cls(lines)


Instruction:
Explain what the following Python 3 code does
def match_file(self, file, separators=None):
		norm_file = util.normalize_file(file, separators=separators)
		return util.match_file(self.patterns, norm_file)

Response: Matches the file to this path - spec.


Instruction:
Explain what the following Python 3 code does
def match_files(self, files, separators=None):
		if isinstance(files, (bytes, unicode)):
			raise TypeError("files:{!r} is not an iterable.".format(files))

		file_map = util.normalize_files(files, separators=separators)
		matched_files = util.match_files(self.patterns, iterkeys(file_map))
		for path in matched_files:
			yield file_map[path]

Response: Matches the files to this path - spec.


Instruction:
Can you implement a function in Python 3 that
walks the specified root path for all files and matches them to thispath - spec.

Response:
def match_tree(self, root, on_error=None, follow_links=None):
		"""
		Walks the specified root path for all files and matches them to this
		path-spec.

		*root* (:class:`str`) is the root directory to search for files.

		*on_error* (:class:`~collections.abc.Callable` or :data:`None`)
		optionally is the error handler for file-system exceptions. See
		:func:`~pathspec.util.iter_tree` for more information.

		*follow_links* (:class:`bool` or :data:`None`) optionally is whether
		to walk symbolik links that resolve to directories. See
		:func:`~pathspec.util.iter_tree` for more information.

		Returns the matched files (:class:`~collections.abc.Iterable` of
		:class:`str`).
		"""
		files = util.iter_tree(root, on_error=on_error, follow_links=follow_links)
		return self.match_files(files)