public async Task Awaiting_Result_Iterates_Source_Task_Predicate()
        {
            var target = new ThrowingAsyncEnumerable <bool>();

            await Assert.ThrowsAsync <NotImplementedException>(async() =>
            {
                await target.SingleOrDefault(QuickFunctions <bool> .IdentityTasked);
            });
        }
        public async Task Awaiting_Result_Iterates_Source()
        {
            var target = new ThrowingAsyncEnumerable <int>();

            await Assert.ThrowsAsync <NotImplementedException>(async() =>
            {
                await target.SingleOrDefault();
            });
        }