Describe how a http handler is treated in server.go

HTTP Handler

func (h *timeoutHandler) ServeHTTP(w ResponseWriter, r *Request) {
  	done := make(chan bool, 1)
		tw := &timeoutWriter{w: w}
		go func() {
			h.handler.ServeHTTP(tw, r)
			done <- true
		}()
		select {
		case <-done:
			return
		case <-h.timeout():
			tw.mu.Lock()
			defer tw.mu.Unlock()
			if !tw.wroteHeader {
				tw.w.WriteHeader(StatusServiceUnavailable)
				tw.w.Write([]byte(h.errorBody()))
			}
			tw.timedOut = true
		}
	}