def test_insert_node_before_head():
ll = LinkedList()
ll.append("apples")
ll.insert_before("apples", "lemons")
assert str(ll) == "{ lemons } -> { apples } -> None"
def test_insert_node_no_value_match():
ll = LinkedList()
ll.append("apples")
ll.insert_before("Blueberries", "lemons")
assert -1
def test_append_node_to_empty_list():
ll = LinkedList()
ll.append("lemons")
assert str(ll) == "{ lemons } -> None"