code: func newBufioWriterPoolWithSize(size int) *BufioWriterPool {
  	return &BufioWriterPool{
  		pool: sync.Pool{
  			New: func() interface{} { return bufio.NewWriterSize(nil, size) },
  		},
  	}
  }
docs: // newBufioWriterPoolWithSize is unexported because new pools should be
  // added here to be shared where required.