docs: def get_message_handler(self, message_handlers):
          """
          Create a MessageHandler for the configured Encoder
          :param message_handlers: a dictionart of MessageHandler keyed by encoder
          :return: a MessageHandler
          """
          encoder = self.options.encoder
          try:
              return message_handlers[encoder]
          except KeyError:
              raise NotImplementedError('No RequestHandler defined for given encoder (%s).' % encoder)