def get_next_id(self):
        try:
            query = {'_id': 'last_id'}
            update = {'$inc': {'id': 1}}
            fn = self.db.internal.find_and_modify
            row = fn(query, update, upsert=True, new=True)
        except Exception as e:
            raise DatabaseException(e)
        return row['id']
def _prefix(kindpats):
    """Whether all the patterns match a prefix (i.e. recursively)"""
    for kind, pat, source in kindpats:
        if kind not in ("path", "relpath"):
            return False
    return True