python中的OptionParser

看例子：

usage = "usage: python %prog [options]"    parser = OptionParser(usage=usage)    parser.add_option('-d', '--device', help="Device serial number.")    parser.add_option('-o', '--osVersion', help="Os version.")    options, args = parser.parse_args(sys.argv)        if options.device is None:        ......    else:        ......            if options.osVersion is None:        osVersion = ......    elif options.osVersion is "1":        osVersion = ......    else:        print "Error"        sys.exit(-1)