...
def main():
    ''' Prepare and run the spider
    Self-test:
    >>> class Args(object):
    ...     pass
    ...
    >>> args = Args()
    >>> args.url = 'www.baidu.com'
    >>> args.depth = 1
    >>> args.logfile = 'testself.log'
    >>> args.loglevel = 4
    >>> args.dbfile = 'testself.db'
    >>> args.num_threads = 1
    >>> args.key = ''
    >>> set_logger(args.loglevel, args.logfile)
    >>> logger.info(vars(args))
    >>> spider = MySpider(args)
    >>> spider.run()
    '''
...
    # Self test
    if args.testself:
        import doctest
        print doctest.testmod()
        return
...