def _optional(self, typeid):
        old_json = self._json
        self._json = {'bit_start': self.used_bits(), 'typeid':typeid}
        self._markers.append({'at':self.used_bits(),'type':'optional(%s)'%str(typeid)})
        exists = self._bool()
        retval = self.instance(typeid) if exists else None
        old_json[self.used_bits()%'optional%i'] = self._json
        self._json = old_json
        return retval
dataset/ETHPy150Open karlgluck/heroes-of-the-storm-replay-parser/s2protocol/decoders.py/BitPackedDecoderDebug._optional/swapped operands of `%`