code: func (w *QWriter) D(n int) {
  	bb, ok := w.w.(*ByteBuffer)
  	if ok {
  		bb.B = strconv.AppendInt(bb.B, int64(n), 10)
  	} else {
  		w.b = strconv.AppendInt(w.b[:0], int64(n), 10)
  		w.Write(w.b)
  	}
  }
docs: // D writes n to w.