code: def build_getter(validator, getter_namespace=None):
      
      def proxy_register(key_name, default=UndefToken, help=None, namespace=None):
          name        = namespace or getter_namespace or config.DEFAULT
          namespace   = config.get_namespace(name)
          return proxy_factory.build(validator, namespace, key_name, default, help)
  
      return proxy_register
docs: Create a getter function for retrieving values from the config cache.
      Getters will default to the DEFAULT namespace.