class_docstr: Base connector class to be extended by all connectors.
docstr: Return the number of columns in the data source that the connector is
  connected to.
code: def columns_count(self):
      """
      Return the number of columns in the data source that the connector is
      connected to.
      """
      raise NotImplementedError
  
imports: from abc import ABC, abstractmethod
  import os
  from ..helpers.df_info import DataFrameType
  from ..helpers.logger import Logger
  from pydantic import BaseModel
  from typing import Optional, Union
label_desc: Use image node_id 9 for calling the BaseConnector obj's underlying member method code with example usage: obj.columns_count() without return types