def error(self, msg):
        sys.stderr.write("%s: error: %s\n" % (self.get_prog_name(), msg))
        self.die_with_usage(msg)
Overrides parent ``OptionParser`` class's ``error()`` method and
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/grizzled/grizzled/cmdline.py/CommandLineParser.error