Variable ReadableStream

ReadableStream: {
    prototype: ReadableStream;
    new (
        underlyingSource: UnderlyingByteSource,
        strategy?: { highWaterMark?: number },
    ): ReadableStream<Uint8Array<ArrayBufferLike>>;
    new <R = any>(
        underlyingSource: UnderlyingDefaultSource<R>,
        strategy?: QueuingStrategy<R>,
    ): ReadableStream<R>;
    new <R = any>(
        underlyingSource?: UnderlyingSource<R>,
        strategy?: QueuingStrategy<R>,
    ): ReadableStream<R>;
}

Type declaration