get closed() {
		            if (!IsWritableStreamDefaultWriter(this)) {
		                return promiseRejectedWith(defaultWriterBrandCheckException('closed'));
		            }
		            return this._closedPromise;
		        }
@param {string} url    The URL that the new response is to originate from.
@param {number} status An optional status code for the response (e.g., 302.)
@returns {Response}    A Response object.