code: def get_Mapping_key_value(mp):
      
      try:
          res = _select_Generic_superclass_parameters(mp, typing.Mapping)
      except TypeError:
          res = None
      if res is None:
          raise TypeError("Has no key/value types: "+type_str(mp))
      else:
          return tuple(res)
docs: Retrieves the key and value types from a PEP 484 mapping or subclass of such.
      mp must be a (subclass of) typing.Mapping.