'_process_args(largs : [string],
rargs : [string],
values : Values)
Process command-line arguments and populate \'values\', consuming
options and arguments from \'rargs\'.  If \'allow_interspersed_args\' is
false, stop at the first non-option argument.  If true, accumulate any
interspersed non-option arguments in \'largs\'.'

def _process_args(self, largs, rargs, values):

    while rargs:
        arg = rargs[0]
        if (arg == '--'):
            del rargs[0]
            return
        if (arg[0:2] == '--'):
            self._process_long_opt(rargs, values)
        elif ((arg[:1] == '-') and (len(arg) > 1)):
            self._process_short_opts(rargs, values)
        elif self.allow_interspersed_args:
            largs.append(arg)
            del rargs[0]
        else:
            return
