mixin_sample.py

class CMixin(object):
    def do_something(self):
        # do something here
        pass


class AHandler(BaseHandler, CMixin):
    def get(self):
        # ...
        self.do_something()
        # ...


class BHandler(BaseHandler, CMixin):
    def get(self):
        # ...
        self.do_something()
        # ...