A list may have any number of elements. List creates and returns an empty list. Its parameter is a variable. Every list must be declared in this way. List can also be used to make an existing list empty, though this causes a memory leak.
Length returns the length of a list.
Enqueue, dequeue and requeue provide queue access to a list. The first parameter to all three is the list. Dequeue removes and returns the element from the front of a queue. Requeue adds an element to the front of a queue. Its second parameter is the element.