export declare class Emitter<E extends Record<string, any>> {
    private _emitter;
    /**
     * Listens to the event.
     * @param {string} event Event name.
     * @param {Function} listener Listener function.
     */
    on<K extends Exclude<keyof E, number>>(event: K, listener: (...args: E[K]) => any): Emitter<E>;
    /**
     * Listens to the event only for once.
     * @param {string} event Event name.
     * @param {Function} listener Listener function.
     */
    once<K extends Exclude<keyof E, number>>(event: K, listener: (...args: E[K]) => any): Emitter<E>;
    /**
     * Emits the event.
     * @param {string} event Event name.
     * @param {any[]} args Listener arguments.
     * @returns {boolean} `true` if the event had listeners, `false` otherwise.
     */
    emit<K extends Exclude<keyof E, number>>(event: K, ...args: E[K]): boolean;
}