code: def check_column(state, name, missing_msg=None, expand_msg=None):
      
  
      if missing_msg is None:
          missing_msg = "We expected to find a column named `{{name}}` in the result of your query, but couldn't."
      if expand_msg is None:
          expand_msg = "Have another look at your query result. "
      msg_kwargs = {"name": name}
  
      # check that query returned something
      has_result(state)
  
      stu_res = state.student_result
      sol_res = state.solution_result
  
      if name not in sol_res:
          raise BaseException("name %s not in solution column names" % name)
  
      if name not in stu_res:
          _msg = state.build_message(missing_msg, fmt_kwargs=msg_kwargs)
          state.do_test(_msg)
  
      return state.to_child(
          append_message={"msg": expand_msg, "kwargs": msg_kwargs},
          student_result={name: stu_res[name]},
          solution_result={name: sol_res[name]},
      )
docs: Zoom in on a particular column in the query result, by name.
  
      After zooming in on a column, which is represented as a single-column query result,
      you can use ``has_equal_value()`` to verify whether the column in the solution query result
      matches the column in student query result.
  
      Args:
          name: name of the column to zoom in on.
          missing_msg: if specified, this overrides the automatically generated feedback
                       message in case the column is missing in the student query result.
          expand_msg: if specified, this overrides the automatically generated feedback 
                      message that is prepended to feedback messages that are thrown
                      further in the SCT chain.
  
      :Example:
  
          Suppose we are testing the following SELECT statements
  
          * solution: ``SELECT artist_id as id, name FROM artists``
          * student : ``SELECT artist_id, name       FROM artists``
  
          We can write the following SCTs: ::
  
              # fails, since no column named id in student result
              Ex().check_column('id')
  
              # passes, since a column named name is in student_result
              Ex().check_column('name')