def test_repr():
    ll = SinglyLinkedList()
    assert (repr(ll) == "Empty")
    for i in range(5):
        ll.insert_tail(i)
    assert(repr(ll) == "0 {data: 0} -> 1 {data: 1} -> "\
        "2 {data: 2} -> 3 {data: 3} -> 4 {data: 4}")
def test_insert_tail():
    ll = SinglyLinkedList()
    for i in range(ITERS):
        ll.insert_tail(i)
        assert (len(ll) == i + 1)
        assert (ll.peek_tail() == i)
def base_ll():
    ll = SinglyLinkedList()
    for i in range(ITERS):
        ll.insert_tail(i)
    return ll