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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def register_actions(self, shortcut_manager):
 """Register callback methods for triggered actions in all child controllers. :param rafcon.gui.shortcut_manager.ShortcutManager shortcut_manager: Shortcut Manager Object holding mappings between shortcuts and actions. """

        assert isinstance(shortcut_manager, ShortcutManager)
        self.__shortcut_manager = shortcut_manager

        for controller in list(self.__child_controllers.values()):
            if controller not in self.__action_registered_controllers:
                try:
                    controller.register_actions(shortcut_manager)
                except Exception as e:
                    logger.error("Error while registering action for {0}: {1}".format(controller.__class__.__name__, e))
                self.__action_registered_controllers.append(controller)