export declare class EventHandler {
    get count(): number;
    private events;
    private lastBlock;
    private interval;
    private polling;
    private lastTimeout;
    private getBlockNumber;
    subscribe(callback: (blockNumber: number) => void, getBlockNumber: () => Promise<number>): {
        unsubscribe: () => void;
    };
    unsubscribe(callback: (blockNumber: number) => void): void;
    private checkBlock;
}