Obtain the backmost node. Removes node if it's in list. Obtain the backmost node, and remove it from list too. Moves node to front of list. Moves node to back of list.
Moves node to front of list.
It can be a new node, or it can be an existing node. Moves node to back of list. It can be a new node, or it can be an existing node. Removes node if it's in list. Does nothing if it's not.