code: func allSpaceWithNewline(str string) bool {
  	var seenNewline = false
  	for _, ch := range str {
  		if !unicode.IsSpace(ch) {
  			return false
  		}
  		if isEndOfLine(ch) {
  			seenNewline = true
  		}
  	}
  	return seenNewline
  }
docs: // allSpaceWithNewline returns true if the entire string consists of whitespace,
  // with at least one newline.