Python: linked lists

gistfile1.py

class Node(object):
    prev = None
    next = None
    value = None
    
    def __init__(self, prev, value):
        self.value = value
        self.appendTo(prev)
    
    def unlink(self):
        if self.prev:
            self.prev.next = self.next
        if self.next:
            self.next.prev = self.prev
        self.prev = None
        self.next = None
    
    def appendTo(self, node):
        self.prev = node
        if node is None:
            return
        if node.next:
            node.next.prev = self
        self.next, node.next = node.next, self
    
    def __iter__(self):
        v = self
        while v is not None:
            yield v
            v = v.next


LinkedList = Node

head = LinkedList(None, None)
head.last = head

# appending
head.last = Node(head.last, 5)

# removing
if head.last == node:
  head.last = node.prev
node.unlink()