Freese screenshot, so all image functions will not take images, until call free_screen()

def keep_screen(self):
        """
        Freese screenshot, so all image functions will not take images, until call free_screen()
        """
        self.__last_screen = self.screenshot()
        self.__keep_screen = True
        inner_self = self

        class _C(object):
            def __enter__(self):
                pass

            def __exit__(self, type, value, traceback):
                inner_self.free_screen()

        return _C()