Fix Append

The model receives the prompt (and optional system message). The run uses scorer contains_all with the JSON configuration below. Pass/fail and partial credit are determined entirely by that scorer against the model output; no human grading.

Fix the bug and return corrected Python code only.

def add_item(items, item):
    items + [item]
    return items

{
  "expected_contains": [
    "items.append(item)",
    "return items"
  ]
}