<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def __generate_wrapper_class(self):
 """ Generates the wrapper class. """

        routines = self._read_routine_metadata()

        self._write_class_header()

        if routines:
            for routine_name in sorted(routines):
                if routines[routine_name]['designation'] != 'hidden':
                    self._write_routine_function(routines[routine_name])
        else:
            self._io.error('No files with stored routines found')

        self._write_class_trailer()

        Util.write_two_phases(self._wrapper_filename, self._code, self._io)