export class BinarySemaphore {
  constructor() {
    this.init();
  }
  post: () => void;
  then: (onSuccess: (val: any) => void, onError: (err: any) => void) => void;
  reset() {
    this.post();
    this.init();
  }
  private init() {
    const promise = new Promise<void>((resolve) => {
      this.post = resolve as () => void;
    });
    this.then = promise.then.bind(promise);
  }
}