code: func (l *line) Add(word string) bool {
  	newLine := line{
  		wrap:  l.wrap,
  		words: append(l.words, word),
  	}
  	if newLine.Len() <= l.wrap || len(l.words) == 0 {
  		l.words = newLine.words
  		return true
  	}
  	return false
  }
docs: // Add adds the word to the line, returns true if we could, false if we
  // didn't have enough room. It's always possible to add to an empty line.