code: def factory(cls, registry):
          
          # This implementation relies on MetricsHandler.registry
          #  (defined above and defaulted to REGISTRY).
  
          # As we have unicode_literals, we need to create a str()
          #  object for type().
          cls_name = str(cls.__name__)
          MyMetricsHandler = type(cls_name, (cls, object),
                                  {"registry": registry})
          return MyMetricsHandler
docs: Returns a dynamic MetricsHandler class tied
             to the passed registry.