class Parent():

    def method(self, param):
        # Bugged
        do_stuff()

class Override(Parent):

    def method(self, param):
        # Fixed (tested)
        param = fix_param(param)
        super(Parent, self).method(param)

class External():

    def processing():
        # Same bug as in `Parent`
        param = get_param()
        obj = Override()
        obj.method(param)