publish pretrain sample step 500

samples/pretrain_step_500.txt

@@ -0,0 +1,26 @@
+<bos><user>Fix the bug in this Python function and explain the change:
+
+```python
+def add(a, b):
+    return a - b
+```
+<assistant>
+    border: {
+    }
+    if (response, 1, '1, 10, x, 0, {
+        }
+
+        }
+        }
+        return null;
+        private void void if (i, {
+        while (int android.add(new 1, 0, {
+    }
+        }
+        }
+        }
+
+        if (String, 100, 1, 0,
+        return self.set(i, 0,
+        }
+        if (int (int self, 0, 0, 0, {