class_docstr: Unit tests for Agent class
code: def test_rephrase(self, sample_df, config):
      agent = Agent(sample_df, config, memory_size=10)
      agent._lake.llm.call = Mock()
      clarification_response = """
  How much has the total salary expense increased?
          """
      agent._lake.llm.call.return_value = clarification_response
  
      response = agent.rephrase_query(
          "how much has the revenue increased?"
      )
  
      assert response == (
          """
  How much has the total salary expense increased?
          """
      )
  
imports: from typing import Optional
  from unittest.mock import Mock
  from pandasai.agent import Agent
  import pandas
  import pytest
  from pandasai.llm.fake import FakeLLM
  from pandasai.prompts.clarification_questions_prompt import ClarificationQuestionPrompt
  from pandasai.prompts.explain_prompt import ExplainPrompt
  from pandasai.smart_datalake import SmartDatalake
label_desc: Use image node_id 21 for calling the TestAgent obj's underlying member method code with example usage: obj.test_rephrase(sample_df, config) without return types