def addWriter(self, writer):
        """
        Implement L{IReactorFDSet.addWriter}.
        """
        fd = writer.fileno()
        if self._writes not in fd:
            try:
                self._updateRegistration(fd, KQ_FILTER_WRITE, KQ_EV_ADD)
            except OSError:
                pass
            finally:
                self._selectables[fd] = writer
                self._writes[fd] = 1
dataset/ETHPy150Open nlloyd/SubliminalCollaborator/libs/twisted/internet/kqreactor.py/KQueueReactor.addWriter/swapped operands of `not in`