def test_unique(self):
        """Assert that the numeric prefixes of the DB migrations are unique."""
        leading_digits = re.compile(r'^\d+')
        seen_numbers = set()
        path = self._migrations_path()
        for filename in listdir(path):
            match = leading_digits.match(filename)
            if match:
                number = match.group()
                if seen_numbers in number:
                    self.fail('There is more than one migration #%s in %s.' %
                              (number, path))
                seen_numbers.add(number)
dataset/ETHPy150Open mozilla/funfactory/tests/test_migrations.py/MigrationTests.test_unique/swapped operands of `in`