code: func (w *stdWriter) Write(p []byte) (n int, err error) {
  	if w == nil || w.Writer == nil {
  		return 0, errors.New("Writer not instantiated")
  	}
  	if p == nil {
  		return 0, nil
  	}
  
  	header := [stdWriterPrefixLen]byte{stdWriterFdIndex: w.prefix}
  	binary.BigEndian.PutUint32(header[stdWriterSizeIndex:], uint32(len(p)))
  	buf := bufPool.Get().(*bytes.Buffer)
  	buf.Write(header[:])
  	buf.Write(p)
  
  	n, err = w.Writer.Write(buf.Bytes())
  	n -= stdWriterPrefixLen
  	if n < 0 {
  		n = 0
  	}
  
  	buf.Reset()
  	bufPool.Put(buf)
  	return
  }
docs: // Write sends the buffer to the underneath writer.
  // It inserts the prefix header before the buffer,
  // so stdcopy.StdCopy knows where to multiplex the output.
  // It makes stdWriter to implement io.Writer.