public async Task LambdaIsNotCalledIfSequenceIsEmpty()
        {
            bool lambdaCalled = false;
            await AsyncEnumerator.Empty <int>().ForEach(_ => lambdaCalled = true).ConfigureAwait(true);

            lambdaCalled.Should().BeFalse();
        }
        public async Task ReturnsEmptyArrayForEmptySequence()
        {
            int[] array = await AsyncEnumerator.Empty <int>().ToArray().ConfigureAwait(true);

            array.Should().BeEmpty();
        }