def _iterator(self):
        for l, h in self.ranges:
            l = self.getnext(1-l)
            while l <= h:
                yield l
                l = self.getnext(l)
                if l is None:
                    break
dataset/ETHPy150Open nlloyd/SubliminalCollaborator/libs/twisted/mail/imap4.py/MessageSet._iterator/swapped operands of `-`