def test_insert_head():
ll = DoublyLinkedList()
for i in range(ITERS):
ll.insert_head(i)
assert (len(ll) == i + 1)
assert (ll.peek_head() == i)
def test_ll_equality():
ll1, ll2 = DoublyLinkedList(), DoublyLinkedList()
for i in range(ITERS):
ll1.insert_head(i)
ll2.insert_head(i)
assert (ll1 == ll2)