export declare type UnsubscribeCallback = {
    (): void;
};
export declare type EmitterCallback<T> = {
    (event: T): void;
};
export interface EventEmitter<T> {
    emit(event: T): void;
    queue(event: T): void;
    listen(callback: EmitterCallback<T>): UnsubscribeCallback;
}
export declare class Emitter<T> {
    private listeners;
    private isEmitting;
    private queuedEvents;
    emit(event: T): void;
    queue(event: T): void;
    listen(callback: EmitterCallback<T>): UnsubscribeCallback;
}
export declare function flatMap<T, V>(transform: (event: T) => Array<V>, source: EventEmitter<T>): EventEmitter<V>;