Downgrade to a revision

def _cmd_down(self):
        """Downgrade to a revision"""
        revision = self._get_revision()
        if not self._rev:
            self._log(0, "downgrading current revision")
        else:
            self._log(0, "downgrading to revision %s" % revision)
        # execute from latest to oldest revision
        for rev in reversed(self._revisions[int(revision) - 1:]):
            sql_files = glob.glob(os.path.join(self._migration_path, rev, "*.down.sql"))
            sql_files.sort(reverse=True)
            self._exec(sql_files, rev)
        self._log(0, "done: downgraded revision to %s" % rev)