def _crc32(self, ch, crc):
        return ((crc >> 8) & 0xffffff) ^ self.crctable[(crc ^ ord(ch)) & 0xff]
Add a pair of callbacks that will be run in the context of an eliot
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/zipfile.py/_ZipDecrypter._crc32--crossover with--dataset/ETHPy150Open ClusterHQ/eliot/eliot/twisted.py/DeferredContext.addCallbacks