public void ObserveAllExceptionsAsync()
 {
     Assert.ThrowsAsync <AggregateException>(async() =>
     {
         await StaticClass.ObserveAllExceptionsAsync();
     });
 }
 public void ObserveOneExceptionAsync()
 {
     Assert.ThrowsAsync <NotImplementedException>(async() =>
     {
         await StaticClass.ObserveOneExceptionAsync();
     });
 }