public void TraverseTest()
{
var qt = new RegionQuadtree <int>(2);
qt.Set(new Point2i(0, 0), 1);
qt.Set(new Point2i(1, 0), 2);
var t = qt.Traverse().ToList();
Assert.Equal(2, t.Count);
qt = new RegionQuadtree <int>(3);
qt.Set(new Point2i(0, 0), 1);
qt.Set(new Point2i(7, 7), 2);
qt.Set(new Point2i(1, 0), 1);
qt.Set(new Point2i(0, 5), 2);
qt.Set(new Point2i(3, 6), 2);
t = qt.Traverse().ToList();
Assert.Equal(5, t.Count);
}