code: def get_attribute_by_repr(self, attribute_repr_name, mapped_class=None,
                                key=None):
          
          attr_map = self.__get_attribute_map(mapped_class, key, 1)
          try:
              return attr_map[attribute_repr_name]
          except KeyError:
              raise AttributeError(attribute_repr_name)
docs: Returns the attribute (specified by its representation name) from
          the map of all mapped attributes for the given mapped class and
          attribute key. See :method:`get_attribute_map` for details.