declare const sw: ServiceWorkerGlobalScope;
interface StreamSaverData {
    headers?: Record<string, string> | [string, string][];
    filename?: string;
    size?: number;
    readableStream?: ReadableStream;
    transferringReadable?: boolean;
    url?: string;
    [key: string]: any;
}
type DownloadMetadata = [stream: ReadableStream | null, data: StreamSaverData, port: MessagePort];
declare const map: Map<string, DownloadMetadata>;
declare function createStream(port: MessagePort): ReadableStream;