export declare function isAsyncIterable(body: any): body is AsyncIterable<any>;
export declare function isReadableStream(stream: any): stream is ReadableStream;
export declare function isRequestInit(val: unknown): val is RequestInit;
export declare function completeAssign(...args: any[]): any;
export declare function addWaitUntil(serverContext: any, waitUntilPromises: Promise<unknown>[]): void;