// The [io.ReadCloser]'s Close method must be used to release associated resources.
// The Decompressor itself must be safe to invoke from multiple goroutines
// simultaneously, but each returned reader will be used only by
// one goroutine at a time.
type Decompressor func(r io.Reader) io.ReadCloser

var flateWriterPool sync.Pool

func newFlateWriter(w io.Writer) io.WriteCloser {