code: func (f TimeFormatChecker) IsFormat(input interface{}) bool {
  	asString, ok := input.(string)
  	if !ok {
  		return false
  	}
  
  	if _, err := time.Parse("15:04:05Z07:00", asString); err == nil {
  		return true
  	}
  
  	_, err := time.Parse("15:04:05", asString)
  	return err == nil
  }
docs: // IsFormat checks if input correctly formatted time (HH:MM:SS or HH:MM:SSZ-07:00)