Runs a command.

        :param cmd: command to run (key at the registry)
        :param argv: arguments that would be passed to the command

def call_command(self, cmd, *argv):
        """
        Runs a command.

        :param cmd: command to run (key at the registry)
        :param argv: arguments that would be passed to the command
        """
        parser = self.get_parser()
        args = [cmd] + list(argv)
        namespace = parser.parse_args(args)
        self.run_command(namespace)