class Application(object):

    def __init__(self):
        print('-> init application')
        self.do_init()
        print('<- init application')


    def do_init(self):
        print('1. app')


class SecondApp(Application):

    def do_init(self):
        print('-> 2. SecondApp')
        super().do_init()
        print('<- 2. SecondApp')


class ThirdApp(Application):

    def do_init(self):
        print('-> 3. ThirdApp')
        super().do_init()
        print('<- 3. ThirdApp')


class FourApp(ThirdApp):

    def do_init(self):
        print('-> 4. FourApp')
        super().do_init()
        print('<- 4. FourApp')


class FiveApp(ThirdApp):

    def do_init(self):
        print('-> 5. FiveApp')
        super().do_init()
        print('<- 5. FiveApp')


class FinApp(SecondApp, FourApp, FiveApp):

    def do_init(self):
        print('-> FinApp')
        super().do_init()
        print('<- FinApp')

testing = FinApp()