code: func (loc *Location) Format(f string, a ...interface{}) string {
  	if len(loc.File) > 0 {
  		f = fmt.Sprintf("%v:%v: %v", loc.File, loc.Row, f)
  	} else {
  		f = fmt.Sprintf("%v:%v: %v", loc.Row, loc.Col, f)
  	}
  	return fmt.Sprintf(f, a...)
  }
docs: // Format returns a formatted string prefixed with the location information.