def delete(self, doc):
        if doc.id is None:
            raise DatabaseException('Document does not have id')
        if doc.sid is None:
            try:
                rs = self.db.docs.remove({'id': doc.id}, safe=True)
                assert rs['n'] == 1
            except Exception as e:
                raise DatabaseException(e)
            return None
        doc.data = None
        return self.update(doc)
def setup_args(parser=None):
    if parser is None:
        parser = ParlaiParser(True, True, 'Check tasks for common errors')
    # Get command line arguments
    parser.add_argument('-ltim', '--log-every-n-secs', type=float, default=2)
    parser.add_argument('-d', '--display-examples', type='bool', default=False)
    parser.set_defaults(datatype='train:stream:ordered')
    return parser