export declare class FlatQueue<GItem> {
    private _ids;
    private _values;
    private _length;
    constructor();
    /**
     * Number of items in the queue.
     */
    get length(): number;
    /**
     * Adds `item` to the queue with the specified `priority`.
     *
     * `priority` must be a number. Items are sorted and returned from low to
     * high priority. Multiple items with the same priority value can be added
     * to the queue, but there is no guaranteed order between these items.
     */
    push(id: GItem, priority: number): void;
    /**
     * Removes and returns the item from the head of this queue, which is one of
     * the items with the lowest priority. If this queue is empty, returns
     * `null`.
     */
    pop(): GItem | null;
}