const string& op_name, GradientFunctionFactory gradient_function_factory) {
  auto iter = registry_.find(op_name);
  if (iter != registry_.end()) {
    const string error_msg = "Gradient already exists for op: " + op_name + ".";
    return errors::AlreadyExists(error_msg);
  }
  registry_.insert({op_name, gradient_function_factory});
  return absl::OkStatus();
}
Status GradientRegistry::Lookup(
    const ForwardOperation& op,

						}
					}
					if programmed {
						break
					}
					if time.Since(startTime) > waitTimeout {
						errorMsg := fmt.Sprintf("timed out while waiting for waypoint %v/%v", gw.Namespace, gw.Name)
						if err != nil {
							errorMsg += fmt.Sprintf(": %s", err)
						}
						return fmt.Errorf(errorMsg)
					}
				}
			}
			fmt.Fprintf(cmd.OutOrStdout(), "waypoint %v/%v applied\n", gw.Namespace, gw.Name)