// writeBlocks writes a specified chunk of symbols to the output buffer. It
// breaks the write up into ≥blockSize chunks to write them out, and schedules
// as many goroutines as necessary to accomplish this task. This call then
// blocks, waiting on the writes to complete. Note that we use the sem parameter
// to limit the number of concurrent writes taking place.

func (h extraHeader) Write(w *bufio.Writer) {
	if h.date != nil {
		w.Write(headerDate)
		w.Write(h.date)
		w.Write(crlf)
	}
	if h.contentLength != nil {
		w.Write(headerContentLength)
		w.Write(h.contentLength)
		w.Write(crlf)
	}
	for i, v := range []string{h.contentType, h.connection, h.transferEncoding} {
		if v != "" {
			w.Write(extraHeaderKeys[i])
			w.Write(colonSpace)