// make the server code a bit more concrete.
type http2writeContext interface {
	Framer() *http2Framer
	Flush() error
	CloseConn() error
	// HeaderEncoder returns an HPACK encoder that writes to the
	// returned buffer.
	HeaderEncoder() (*hpack.Encoder, *bytes.Buffer)
}

// writeEndsStream reports whether w writes a frame that will transition