code: def list_parameters(self, parameter_type=None, page_size=None):
          
          params = {'details': True}
  
          if parameter_type is not None:
              params['type'] = parameter_type
          if page_size is not None:
              params['limit'] = page_size
  
          return pagination.Iterator(
              client=self._client,
              path='/mdb/{}/parameters'.format(self._instance),
              params=params,
              response_class=mdb_pb2.ListParametersResponse,
              items_key='parameter',
              item_mapper=Parameter,
          )
docs: Lists the parameters visible to this client.
  
          Parameters are returned in lexicographical order.
  
          :param str parameter_type: The type of parameter
          :rtype: :class:`.Parameter` iterator