code: func (dr *StreamReporter) Report(key, value string, resultType ValidationResultType) error {
  	var c color
  	switch resultType {
  	case good:
  		c = green
  	case bad:
  		c = red
  	case warn:
  		c = yellow
  	default:
  		c = white
  	}
  	if dr.WriteStream == nil {
  		return errors.New("WriteStream has to be defined for this reporter")
  	}
  
  	fmt.Fprintf(dr.WriteStream, "%s: %s\n", colorize(key, white), colorize(value, c))
  	return nil
  }
docs: // Report reports validation result in different color depending on the result type.