code: func HTMLEscape(w io.Writer, b []byte) {
  	last := 0
  	for i, c := range b {
  		var html []byte
  		switch c {
  		case '"':
  			html = htmlQuot
  		case '\'':
  			html = htmlApos
  		case '&':
  			html = htmlAmp
  		case '<':
  			html = htmlLt
  		case '>':
  			html = htmlGt
  		default:
  			continue
  		}
  		w.Write(b[last:i])
  		w.Write(html)
  		last = i + 1
  	}
  	w.Write(b[last:])
  }
docs: // HTMLEscape writes to w the escaped HTML equivalent of the plain text data b.