Consume individual protocol message fragments.

        Args:
            fragment (``JSON``) :
                A message fragment to assemble. When a complete message is
                assembled, the receiver state will reset to begin consuming a
                new message.

def consume(self, fragment):
        ''' Consume individual protocol message fragments.

        Args:
            fragment (``JSON``) :
                A message fragment to assemble. When a complete message is
                assembled, the receiver state will reset to begin consuming a
                new message.

        '''
        self._current_consumer(fragment)
        raise gen.Return(self._message)