code: def df_short():
      return pd.DataFrame(
          {
              "id": ["id1", "id2", "id3", "id4"],
              "parent_id": ["None", "id1", "id2", "id3"],
              "answer": ["answer1", "answer2", "answer3", "answer4"],
              "system": ["system1", "system2", "system3", "system4"],
              "prompt": ["prompt1", "prompt2", "prompt3", "prompt4"],
          }
      )
  
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 2 for calling a global function with example usage: df_short() and returns: pd