code: def register_composer(self, type, composer, **meta):
          
          try:
              self.registered_formats[type]['composer'] = composer
          except KeyError:
              self.registered_formats[type] = {'composer': composer}
          if meta:
              self.register_meta(type, **meta)
docs: Registers a composer of a format.
  
          :param type: The unique name of the format
          :param composer: The method to compose data as the format