export type PusherSocketIdFactory<Req = any> = (req: Req) => string;
/**
 * Decorators the function to customize the socket id factory
 * @default Header value (x-pusher-sid)
 * @param factory Either provide the header name or a custom factory function
 */
export declare function PusherSocketId(factory: string | PusherSocketIdFactory): MethodDecorator;