'This method adjusts the ordering of the doubly linked list so that
\'node\' directly precedes the \'head\' node. Because of the order of
operations, if \'node\' already directly precedes the \'head\' node or if
\'node\' is the \'head\' node the order of the list will be unchanged.'

def move_to_front(self, node):

    node.prev.next = node.next
    node.next.prev = node.prev
    node.prev = self.head.prev
    node.next = self.head.prev.next
    node.next.prev = node
    node.prev.next = node
