push(bucket, item, options) {
        const callback = options.callback || process.nextTick;
        if (!this.queues[bucket]) {
            this.queues[bucket] = new Deque$1();
        }
        const queue = this.queues[bucket];
        queue.push(item);
        if (!this.timeouts[bucket]) {
            this.timeouts[bucket] = setTimeout(() => {
                callback(() => {
                    this.timeouts[bucket] = null;
                    this.execute(bucket);
                });
            }, options.timeout);
        }
    }
Add a new item to the queue

@param {string} bucket bucket name
@param {Function} item function that will run later
@param {IDelayQueueOptions} options
@memberof DelayQueue