code: func WriteVarBytes(w io.Writer, pver uint32, bytes []byte) error {
  	slen := uint64(len(bytes))
  	err := WriteVarInt(w, pver, slen)
  	if err != nil {
  		return err
  	}
  
  	_, err = w.Write(bytes)
  	return err
  }
docs: // WriteVarBytes serializes a variable length byte array to w as a varInt
  // containing the number of bytes, followed by the bytes themselves.