code: func WriteVarString(w io.Writer, pver uint32, str string) error {
  	err := WriteVarInt(w, pver, uint64(len(str)))
  	if err != nil {
  		return err
  	}
  	_, err = w.Write([]byte(str))
  	return err
  }
docs: // WriteVarString serializes str to w as a variable length integer containing
  // the length of the string followed by the bytes that represent the string
  // itself.