code: def get_pk_attrnames(obj) -> List[str]:
      
      return [attrname
              for attrname, column in gen_columns(obj)
              if column.primary_key]
docs: Asks an SQLAlchemy ORM object: "what are your primary key(s)?"
  
      Args:
          obj: SQLAlchemy ORM object
  
      Returns:
          list of attribute names of primary-key columns