middleware/throttle.go
func Throttle(limit int) func(http.Handler) http.Handler {
	return ThrottleBacklog(limit, 0, defaultBacklogTimeout)
}
func Throttle(limit int) func(http.Handler) http.Handler {
	return ThrottleBacklog(limit, 0, defaultBacklogTimeout)
}
// Throttle is a middleware that limits number of currently processed requests
// at a time.