code: func ToBytes(keys string) ([]byte, error) {
  	codes := []byte{}
  next:
  	for _, key := range strings.Split(keys, ",") {
  		if len(key) != 1 {
  			for code, ctrl := range ASCII {
  				if ctrl == key {
  					codes = append(codes, byte(code))
  					continue next
  				}
  			}
  			if key == "DEL" {
  				codes = append(codes, 127)
  			} else {
  				return nil, fmt.Errorf("Unknown character: '%s'", key)
  			}
  		} else {
  			codes = append(codes, key[0])
  		}
  	}
  	return codes, nil
  }
docs: // ToBytes converts a string representing a suite of key-sequence to the corresponding ASCII code.