class LinkedQueue: def __init__(self): self._items = LinkedList() def is_empty(self): return len(self._items) == 0 def __len__(self): return len(self._items) def __iter__(self): iter(self._items) def clear(self): self._items = LinkedList() def add_front(self, item): self._items.append_head(item) def add_rear(self, item): self._items.append(item) def remove_front(self): return self._items.pop_head() def remove_rear(self): return self._items.pop_tail()