<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def register(action):
 """Action registration is used to support generating lists of permitted actions from a permission set and an object pattern. Only registered actions will be returned by such queries. """

        if isinstance(action, str):
            Action.register(Action(action))
        elif isinstance(action, Action):
            Action.registered.add(action)
        else:
            for a in action:
                Action.register(a)