"""This example shows the use of a mixin class"""

class Displayer():

    def display(self, message):
        print(message)

class LoggerMixin():

    def log(self, message, filename='logfile.txt'):
        with open(filename, 'a') as fh:
            fh.write(message)

    def display(self, message):
        super().display(message)
        self.log(message)

class MySubClass(LoggerMixin, Displayer):

    def log(self, message):
        super().log(message, filename='subclasslog.txt')


subclass = MySubClass()
subclass.display("This string will be shown and logged in subclasslog.txt.")