public void Lookup_SingleElementAdded_ReturnsTrue(TestType value, Guid tag)
        {
            _orSetService.DownstreamAdd(value, tag);

            var lookup = _orSetService.Lookup(value);

            Assert.True(lookup);
        }
        public void Lookup_SingleElementAdded_ReturnsTrue(OR_SetElement <TestType> value)
        {
            _orSetService.Merge(new HashSet <OR_SetElement <TestType> > {
                value
            }.ToImmutableHashSet(), ImmutableHashSet <OR_SetElement <TestType> > .Empty);

            var lookup = _orSetService.Lookup(value.Value);

            Assert.True(lookup);
        }