code: def column_hash(self):
      return "some_hash_value"
  
imports: import pytest
  from pandasai.connectors import BaseConnector
  from pandasai.connectors.base import BaseConnectorConfig
  from pandasai.helpers import Logger
label_desc: Use image node_id 7 for calling the MockConnector obj's underlying member method code with example usage: obj.column_hash() and returns: str