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 _expandsets(kindpats, ctx):
    """Returns the kindpats list with the 'set' patterns expanded."""
    fset = set()
    other = []

    for kind, pat, source in kindpats:
        if kind == "set":
            if not ctx:
                raise error.ProgrammingError("fileset expression with no " "context")
            s = ctx.getfileset(pat)
            fset.update(s)
            continue
        other.append((kind, pat, source))
    return fset, other