code: def is_handler(cls, name, value):
          
          signal_name = False
          config = None
          if callable(value) and hasattr(value, SPEC_CONTAINER_MEMBER_NAME):
                  spec = getattr(value, SPEC_CONTAINER_MEMBER_NAME)
                  if spec['kind'] == 'handler':
                      signal_name = spec['name']
                      config = spec['config']
          return signal_name, config
docs: Detect an handler and return its wanted signal name.