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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def unlink(self):
        '''Remove this node and link any head or tail.'''
        old_head = self.head
        old_tail = self.tail

        self.head = None
        self.tail = None

        if old_head:
            old_head.tail = old_tail

        if old_tail:
            old_tail.head = old_head