| import optparse | 
 |  | 
 | class OptionParser (optparse.OptionParser): | 
 |  | 
 |     def check_required (self, opt): | 
 |         option = self.get_option(opt) | 
 |  | 
 |         # Assumes the option's 'default' is set to None! | 
 |         if getattr(self.values, option.dest) is None: | 
 |             self.error("%s option not supplied" % option) | 
 |  | 
 |  | 
 | parser = OptionParser() | 
 | parser.add_option("-v", action="count", dest="verbose") | 
 | parser.add_option("-f", "--file", default=None) | 
 | (options, args) = parser.parse_args() | 
 |  | 
 | print "verbose:", options.verbose | 
 | print "file:", options.file | 
 | parser.check_required("-f") |