code: def df():
      return pd.DataFrame(
          {
              "id": [
                  "id1",
                  "id2",
                  "id3",
                  "id4",
                  "x1",
                  "x2",
                  "x3",
                  "x4",
              ],
              "parent_id": [
                  "None",
                  "id1",
                  "id2",
                  "id3",
                  "None",
                  "x1",
                  "x2",
                  "x3",
              ],
              "answer": [
                  "answer1",
                  "answer2",
                  "answer3",
                  "answer4",
                  "a1",
                  "a2",
                  "a3",
                  "a4",
              ],
              "system": [
                  "system1",
                  "system2",
                  "system3",
                  "system4",
                  "s1",
                  "s2",
                  "s3",
                  "s4",
              ],
              "prompt": [
                  "prompt1",
                  "prompt2",
                  "prompt3",
                  "prompt4",
                  "p1",
                  "p2",
                  "p3",
                  "p4",
              ],
          }
      )
  
file_path: h2o-llmstudio/tests/src/datasets/test_conversation_chain_handler.py
imports: import time
  from unittest import mock
  from unittest.mock import MagicMock
  import pandas
  import pytest
  from llm_studio.app_utils.default_datasets import prepare_default_dataset_causal_language_modeling
  from llm_studio.src.datasets.conversation_chain_handler import ConversationChainHandler
label_desc: Use image node_id 1 for calling a global function with example usage: df() and returns: pd