export declare class Metric {
    private metric;
    private interval;
    constructor(defaultKeys?: string[]);
    has(key: string): boolean;
    inc(key: string, value?: number): void;
    set(key: string, value?: number): void;
    _interval(left: number, callbackUrl?: string): void;
    startInterval(calculateLeftCb: () => number, interval?: number, callbackUrl?: string): void;
    stopInterval(): void;
}