code: public void writeBytes(byte header, byte[] bytes) {
      int length = bytes.length;
      while (remaining() < length + 10) {
        grow();
      }
      writeLength(length + 1);
      buf[position++] = header;
      System.arraycopy(bytes, 0, buf, position, length);
      position += length;
    }
docs: Write bytes.
  
  @param header header byte
  @param bytes  command bytes