compression.go
func (pool *DeflatePool) ReturnWriter(writer *flate.Writer) {
	writer.Close()
	pool.pool.Put(writer)
}
func (pool *DeflatePool) ReturnWriter(writer *flate.Writer) {
	writer.Close()
	pool.pool.Put(writer)
}
// ReturnWriter returns a flate.Writer to the pool that can
// late be reused via GetWriter.
// Don't close the writer, Flush will be called before returning
// it to the pool.