def test_point_centroid(self):
p1 = Point(1, 2, 3)
p2 = Point(1, 5, 6)
p3 = Point(1, 2, 3)
self.assertEqual(Point.centroid((p1, p2, p3)), Point(1, 3, 4))
p1 = Point(1, 2, 3)
p2 = Point(1, 5, 6)
p3 = Point(1, 2, 3)
p4 = Point(1, 2, 3)
self.assertEqual(Point.centroid((p1, p2, p3, p4)),
Point(1, 2.75, 3.75))
