docs: def sorted_converters_keys(self):
          """doufo.ConvertDict().sorted_converters_key: sort converter keys  
          sort key according to their relationship (if parent- and child-class)   
              or their hash value.
          Args:  
              `self`  
          """
          keys = sorted(self.converters.keys(),
                        key=cmp_to_key(tuple_type_compare))
          return {k: self.converters[k] for k in keys}