message: Fix signature of sleep utility
diff: @@ -15,7 +15,7 @@ limitations under the License.
  */
  // Returns a promise which resolves with a given value after the given number of ms
  -export function sleep<T>(ms: number, value: T): Promise<T> {
  +export function sleep<T>(ms: number, value?: T): Promise<T> {
  return new Promise((resolve => { setTimeout(resolve, ms, value); }));
  }
  