interface ReadableStreamDefaultReaderType ParametersoptionalR = anyPropertiesreadonlyclosed: Promise<void>Methodscancel(reason?: any): Promise<void>read(): Promise<ReadableStreamDefaultReadResult<R>>releaseLock(): voidvariable ReadableStreamDefaultReadertype{ readonly prototype: ReadableStreamDefaultReader; new <R>(stream: ReadableStream<R>): ReadableStreamDefaultReader<R>; }