def test_max_withNotEmptyTree_shouldReturnLargestKeyFromTree(self):
bst = Treap()
for i in range(1, 20):
bst.put(i, i)
self.assertEqual(i, bst.max())
def test_max_withEmptyTree_shouldReturnNone(self):
bst = Treap()
self.assertIsNone(bst.max())