/**
 * A listener for a given event.
 */
export declare type Listener<E> = (event: E) => void;
/**
 * An emitter of asynchronous events.
 */
export default class AsyncEmitter<E> {
    private listeners;
    /**
     * Add a listener to the emitter.
     *
     * @param listener - The listener.
     * @returns `this`.
     */
    on(listener: Listener<E>): this;
    /**
     * Add a listener to the emitter.
     *
     * @param listener - The listener.
     * @returns `this`.
     * @see #on
     */
    addListener(listener: Listener<E>): this;
    /**
     * Remove the listener from the emitter.
     *
     * @param listener - The listener.
     * @returns `this`.
     */
    off(listener: Listener<E>): this;
    /**
     * Remove the listener from the emitter.
     *
     * @param listener - The listener.
     * @returns `this`.
     * @see #off
     */
    removeListener(listener: Listener<E>): this;
    /**
     * Emit an event to all listener.
     *
     * @param e - The event.
     * @returns `this`.
     */
    emit(e: E): Promise<void>;
}