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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 offset(self, n):
 """ Return a sibling element offset by n :rtype: :class:`Element` | ``None`` """


        idx = self.index
        if idx is not None:
            sibling = idx + n
            container = self.container
            if 0 <= sibling < len(container):
                return container[sibling]