src/vs/workbench/api/common/extHostFileSystemEventService.ts/ExtHostFileSystemEventService/_createWillExecuteEvent
class ExtHostFileSystemEventService:	private _createWillExecuteEvent<E extends IWaitUntil>(extension: IExtensionDescription, emitter: AsyncEmitter<E>): Event<E> {
		return (listener, thisArg, disposables) => {
			const wrappedListener: IExtensionListener<E> = function wrapped(e: E) { listener.call(thisArg, e); };
			wrappedListener.extension = extension;
			return emitter.event(wrappedListener, undefined, disposables);
		};
	}