export declare class Event<T> {
    protected handlers: ((data?: T) => void)[];
    protected singleHandlers: ((data?: T) => void)[];
    on(handler: (data?: T) => void): void;
    once(handler: (data?: T) => void): void;
    wait(): Promise<void>;
    off(handler: (data?: T) => void): void;
    allOff(): void;
    trigger(data?: T): void;
    hasListener(): boolean;
}