code: def sample_df(self):
      return pd.DataFrame(
          {
              "country": [
                  "United States",
                  "United Kingdom",
                  "France",
                  "Germany",
                  "Italy",
                  "Spain",
                  "Canada",
                  "Australia",
                  "Japan",
                  "China",
              ],
              "gdp": [
                  19294482071552,
                  2891615567872,
                  2411255037952,
                  3435817336832,
                  1745433788416,
                  1181205135360,
                  1607402389504,
                  1490967855104,
                  4380756541440,
                  14631844184064,
              ],
              "happiness_index": [
                  6.94,
                  7.16,
                  6.66,
                  7.07,
                  6.38,
                  6.4,
                  7.23,
                  7.22,
                  5.87,
                  5.12,
              ],
          }
      )
  
imports: import json
  import os
  import time
  from typing import Optional
  from unittest.mock import MagicMock, Mock, patch
  import pandas
  import pytest
  from pandasai.helpers.query_exec_tracker import QueryExecTracker
  from pandasai.llm.fake import FakeLLM
  from pandasai.smart_dataframe import SmartDataframe
  from unittest import TestCase
  from datetime import datetime, timedelta
label_desc: Use image node_id 2 for calling the TestQueryExecTracker obj's underlying member method code with example usage: obj.sample_df() and returns: pd