def write_fileno(self):
        raise NotImplementedError()
Returns the return value which is the first element of the signature
dataset/ETHPy150Open CouchPotato/CouchPotatoServer/libs/tornado/platform/interface.py/Waker.write_fileno--crossover with--dataset/ETHPy150Open fp7-ofelia/ocf/optin_manager/src/python/openflow/common/rpc4django/rpcdispatcher.py/RPCMethod.get_returnvalue