code: def attrname_to_colname_dict(cls) -> Dict[str, str]:
      
      attr_col = {}  # type: Dict[str, str]
      for attrname, column in gen_columns(cls):
          attr_col[attrname] = column.name
      return attr_col
docs: Asks an SQLAlchemy class how its attribute names correspond to database
      column names.
  
      Args:
          cls: SQLAlchemy ORM class
  
      Returns:
          a dictionary mapping attribute names to database column names