Interface Emitter

interface Emitter {
    listen(type: EventName, handler: Handler): void;
    emit(type: string, ...args: any[]): any[];
    emitReduce(type: string, source: any, ...args: any[]): any;
    addEventType(type: string): void;
    removeEventHandler(type: string, handler?: Handler): void;
    getEvents(): Map<string, Handler[] | undefined>;
    holdEventInvoke(fn: () => void): void;
}