Analagous to add(), however, we do not use the standard naming convention, to
avoid interface clashe
Fastest way to tell if the queue is drained.
Removes all items in the queue. head = tail;
Manually remove the item from queue. O(n) performance.
Analagous to poll(); retrieves and removes head. We avoid the use of standard
queue naming methods,
Check if this queue contains the given item. O(n) performance. You may want to
use a Set unless you
Return a count of items in the queue. Default implementation uses a counter;
subclasses may have O(n