def test_zero(self):
     res = distance(0, 0, 0, 0)
     self.assertEqual(res, 0)
 def test_my_four(self):
     res = distance(0, 0, -1, 0)
     self.assertGreaterEqual(res, 0)
 def test_my_six(self):
     res = distance(0, 0, 0, -1)
     self.assertGreaterEqual(res, 0)
 def test_my_two(self):
     res = distance(-1, 0, 0, 0)
     self.assertGreaterEqual(res, 0)
 def test_my_five(self):
     res = distance(5, 5, 5, 5)
     self.assertEqual(res, 0)
 def test_my_one(self):
     res = distance(-1, -1, -1, -1)
     self.assertGreaterEqual(res, 0)
 def test_two(self):
     res = distance(0, 0, 1, 1)
     self.assertEqual(res, 2**0.5)
 def test_one(self):
     res = distance(0, 0, 0, 1)
     self.assertEqual(res, 1)