public void InitialSegments ()
{
#region InitialSegments
IEnumerable<IEnumerable<char>> e = "abc".InitialSegments ();
var l = e.ToList ();
Assert.AreEqual (4, l.Count);
AssertAreSame (new char[]{}, l [0]);
AssertAreSame (new[]{'a'}, l [1]);
AssertAreSame (new[]{'a', 'b'}, l [2]);
AssertAreSame (new[]{'a', 'b', 'c'}, l [3]);
#endregion
}