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. Push and pop provide stack access to a list. The first parameter to both is a list.
Push pushes an element on the stack.
The second parameter to push is the element. Pop removes and returns the most recently pushed element from the stack. The first parameter to both is a list, and the second parameter to both is an integer index into the array. Setel sets a value of an array element. The third parameter to setel is the value to assign to the array element.