def next(self):
        if not self._cached:
            if not self._impl and self.stateless_rpc:
                return None
            return self._impl.next()
        self._cache_index += 1
        if self._cache_index > len(self._cache):
            return None
        return self._cache[self._cache_index]
dataset/ETHPy150Open natestedman/Observatory/observatory/lib/dulwich/server.py/ProtocolGraphWalker.next/original