public void TestReverse()
{
var random = new Random();
ImmutableSortedTreeSet <int> .Builder set = ImmutableSortedTreeSet.CreateBuilder <int>();
for (int i = 0; i < 4 * 8 * 8; i++)
{
int item = random.Next();
set.Add(item);
}
IEnumerable <int> reversed = set.Reverse();
Assert.Equal(set.AsEnumerable().Reverse(), reversed);
Assert.Equal(set, reversed.Reverse());
}