getopt(args, options[, long_options]) -> opts, args
This function works like getopt(), except that GNU style scanning
mode is used by default. This means that option and non-option
arguments may be intermixed. The getopt() function stops
processing options as soon as a non-option argument is
encountered.
If the first character of the option string is '+', or if the
environment variable POSIXLY_CORRECT is set, then option
processing stops as soon as a non-option argument is encountered.