fromtypingimportUnionclassBaseNode:next:Union["BaseNode",None]=None@staticmethoddefadd(node:"BaseNode")->None:ifBaseNode.nextisNone:BaseNode.next=nodereturncurrent=BaseNode.nextwhilecurrent.nextisnotNone:current=current.nextcurrent.next=node@staticmethoddefremove(node:"BaseNode")->None:ifBaseNode.nextisNone:returncurrent=BaseNode.nextprev=BaseNodewhileTrue:ifcurrentisNone:returnifcurrent==node:ifcurrent.nextisnotNone:prev.next=current.nextelse:prev.next=Nonereturnprev=currentcurrent=current.nextclassNode(BaseNode):def__init__(self)->None:self.next=NoneBaseNode.add(self)def__del__(self)->None:BaseNode.remove(self)defmain()->None:Node()Node()if__name__=="__main__":main()

classBaseNode:next=NoneclassNode(BaseNode):def__init__(self)->None:ifBaseNode.nextisNone:BaseNode.next=selfreturnBaseNode.next.next=selfdef__del__(self)->None:BaseNode.next=BaseNode.next.nextNode()Node()

classBaseNode:def__del__(self):print("next",BaseNode.next)print("del",self)BaseNode.next=BaseNode()BaseNode.next.next=BaseNode()

next <__main__.BaseNode object at 0x717fb2d23a10>del <__main__.BaseNode object at 0x717fb2d23a10>next <__main__.BaseNode object at 0x717fb2d23a10> use after freedel <__main__.BaseNode object at 0x717fb2d23a50>