type Handler<T> = (value?: T) => void;
export declare class EventEmitter<T> {
    private _handlersByName;
    constructor();
    emit<K extends keyof T>(name: K, value?: T[K]): void;
    disposableOn<K extends keyof T>(name: K, callback: Handler<T[K]>): () => void;
    on<K extends keyof T>(name: K, callback: Handler<T[K]>): void;
    off<K extends keyof T>(name: K, callback: Handler<T[K]>): void;
    onFirstSubscriptionAdded<K extends keyof T>(name: K): void;
    onLastSubscriptionRemoved<K extends keyof T>(name: K): void;
}
export declare function tests(): {
    test_on_off(assert: any): void;
    test_emit_value(assert: any): void;
    test_double_on(assert: any): void;
};
export {};