writer

type GzipWriter interface {
	Write(p []byte) (int, error)
	Close() error
	Flush() error
}

type GzipWriterExt interface {
	GzipWriter

	// SetHeader will populate header fields with non-nil values in h.
	SetHeader(h Header)
}

type GzipWriterFactory struct {
	// Must return the minimum and maximum supported level.
	Levels func() (min, max int)

	// New must return a new GzipWriter.
	// level will always be within the return limits above.
	New func(writer io.Writer, level int) GzipWriter
}

type Header struct {
	Comment string    // comment
	Extra   []byte    // "extra data"
	ModTime time.Time // modification time
	Name    string    // file name
	OS      byte      // operating system type
}