code: def composer(self, type, **meta):
          
          def decorator(f):
              self.register_composer(type, f)
              if meta:
                  self.register_meta(type, **meta)
              return f
          return decorator
docs: Registers the decorated method as the composer of a format.
  
          :param type: The unique name of the format
          :param meta: The extra information associated with the format