code: func quadsString(tagged []tag.Token) string {
  	tagQuads := ""
  	for _, tok := range tagged {
  		padding := ""
  		pos := tok.Tag
  		switch len(pos) {
  		case 0:
  			padding = "____" // should not exist
  		case 1:
  			padding = "___"
  		case 2:
  			padding = "__"
  		case 3:
  			padding = "_"
  		case 4: // no padding required
  		default:
  			pos = pos[:4] // longer than 4 ... truncate!
  		}
  		tagQuads += pos + padding
  	}
  	return tagQuads
  }
docs: // quadString creates a string containing all of the tags, each padded to 4
  // characters wide.