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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 peek(self):
 """ Returns PeekableIterator.Nothing when the iterator is exhausted. """

        try:
            v = next(self._iter)
            self._iter = itertools.chain((v,), self._iter)
            return v
        except StopIteration:
            return PeekableIterator.Nothing