<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def _update_dict(self, dict_):
        '''
        Update without allowing undefined options or overwrite of class methods
        '''
        dict_ = dict((k, v) for k, v in dict_.items() if (
                    k not in self._init_attrs))

        # zzz
        if 'no_gpg' in dict_ and dict_['no_gpg']:
            dict_['gpg'] = False

        unknown_opts = set(dict_.keys()).difference(set(DEFAULT_OPTS.keys()))
        if unknown_opts and self._print_errors:
            # only print error once
            sys.stdout.write(
                'WARNING: Unknown options: ' +
                ', '.join(list(unknown_opts)) + '\n')
            if 'no_schedule' in unknown_opts:
                sys.stdout.write('WARNING: Config option `no_schedule` has '
                                 'been deprecated. To disable automatic '
                                 'scheduling for Red Hat Insights, run '
                                 '`insights-client --disable-schedule`\n')
        for u in unknown_opts:
            dict_.pop(u, None)
        self.__dict__.update(dict_)