def registered? name
      registration_map = namespaces.map do |namespace|
        registered_in_namespace? name, namespace
      end
      registration_map.any?
    end
def registered? name
      registration_map = namespaces.map do |namespace|
        registered_in_namespace? name, namespace
      end
      registration_map.any?
    end
Query if a callback of given name is registered in any namespace
 @param [ Symbol ] name The name of the callback to check