export interface ReadonlyEmitter<EventMap> {
  on<K extends keyof EventMap>(
    type: K | '*',
    listener: (event: EventMap[K]) => unknown,
    order?: number,
  ): this;
  once<K extends keyof EventMap>(
    type: K | '*',
    listener: (event: EventMap[K]) => unknown,
    order?: number,
  ): this;
  off<K extends keyof EventMap>(type: K | '*', listener: (event: EventMap[K]) => unknown): this;
}

export interface Emitter<EventMap> extends ReadonlyEmitter<EventMap> {
  emit<K extends keyof EventMap>(type: K, event: EventMap[K]): void;
}