A skip list container class in Python

The special .__iter__() method returns an iterator that walks the entire skip list in order. The logic is trivial: we pass the successor of the level-0 list head to the _SkipListIterator constructor. See Section 4.4, “The _SkipListIterator class”.

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    def __iter__ ( self ):
        """Iterator for the entire list"""
        return _SkipListIterator ( self.__heads.links[0] )