def peek(self):
try:<EOL><INDENT>v = next(self._iter)<EOL>self._iter = itertools.chain((v,), self._iter)<EOL>return v<EOL><DEDENT>except StopIteration:<EOL><INDENT>return PeekableIterator.Nothing<EOL><DEDENT>
Returns PeekableIterator.Nothing when the iterator is exhausted.