func NewWeighted(n int64) *Weighted {
	w := &Weighted{size: n}
	return w
}

// Weighted provides a way to bound concurrent access to a resource.
// The callers can request access with a given weight.
type Weighted struct {
	size    int64
	cur     int64
	mu      sync.Mutex
	waiters list.List
}

// Acquire acquires the semaphore with a weight of n, blocking until resources