code: func Notify(err interface{}, extra ...interface{}) (string, error) {
  	return DefaultClient.Notify(newError(err, 2), extra...)
  }
docs: // Notify reports the error err to the Honeybadger service.
  //
  // The first argument err may be an error, a string, or any other type in which
  // case its formatted value will be used.
  //
  // It returns a string UUID which can be used to reference the error from the
  // Honeybadger service, and an error as a second argument.