code: func (r *ValidationResult) Message(message string, args ...interface{}) *ValidationResult {
  	if r.Error != nil {
  		if len(args) == 0 {
  			r.Error.Message = message
  		} else {
  			r.Error.Message = fmt.Sprintf(message, args...)
  		}
  	}
  	return r
  }
docs: // Message sets the error message for a ValidationResult. Returns itself to
  // allow chaining.  Allows Sprintf() type calling with multiple parameters