code: func urlDecode(b []byte) []byte {
  	res := b
  	resi := 0
  	for i := 0; i < len(b); i++ {
  		if b[i] != '%' {
  			res[resi] = b[i]
  			resi++
  			continue
  		}
  		res[resi] = unhex(b[i+1])<<4 | unhex(b[i+2])
  		resi++
  		i += 2
  	}
  	return res[:resi]
  }
docs: // Decode % escaped URL format