public void TestAddRange()
{
int[] expected = { 600, 601, 602, 603, 700, 701, 702, 703, 800, 801, 802, 803 };
ImmutableSortedTreeList <int> .Builder list = ImmutableSortedTreeList.CreateBuilder <int>();
list.AddRange(expected);
Assert.Equal(expected.Length, list.Count);
int[] actual = list.ToArray();
Assert.Equal(expected, actual);
Assert.Throws <ArgumentNullException>(() => list.AddRange(null !));
}