ReadableStreamDefaultReader

interface ReadableStreamDefaultReader <R = any> {

readonly closed: Promise<void>;
cancel(reason?: any): Promise<void>;
read(): Promise<ReadableStreamReadResult<R>>;
releaseLock(): void;
}

var ReadableStreamDefaultReader: {
prototype: ReadableStreamDefaultReader; 
new <R>(stream: ReadableStream<R>): ReadableStreamDefaultReader<R>; 
};