def test_get_node_raises_an_exception_with_invalid_index(self):
lst = LinkedList([1, 2, 3])
with self.assertRaises(IndexError):
lst.get_node(5)
def test_get_node(self):
my_list = [1,2,3,4]
lst = LinkedList(my_list)
self.assertEqual(lst.get_node(-1).elem, 4)