def test_insert_top(self):
linked = LinkedList(['two', 3])
linked.insert_to_the_top(1)
self.assertEqual(1, linked.first_node.data)
self.assertEqual('two', linked.first_node.next.data)
def test_insert_top_empty_list(self):
linked = LinkedList([])
linked.insert_to_the_top('first')
self.assertEqual('first', linked.first_node.data)
self.assertEqual(None, linked.first_node.next)
