public void TestTrueForAll()
{
ImmutableSortedTreeList <int> .Builder list = ImmutableSortedTreeList.CreateBuilder <int>();
Assert.True(list.TrueForAll(i => false));
Assert.Throws <ArgumentNullException>(() => list.TrueForAll(null !));
list.Add(1);
Assert.True(list.TrueForAll(i => i > 0));
Assert.False(list.TrueForAll(i => i <= 0));
}