; void pop(): Destroys the last node in the list. Should do '''NOTHING''' if the list is currently empty. Should decrement size if a node was destroyed. '''NOTE:''' If a node was destroyed, make sure that '''ANY POINTERS POINTING TO IT''', that your code has access to, are set to NULL.
; void clear(): Destroys all nodes in the list. Has no effect if the list is currently empty. When this function is finished, head should point to NULL and size should be 0.