[O] There can only be one item with priority 1?

[Fredrik]

When I think about priority I want to see if one item is more 
prioritized then another. So if I have a list like this:

* TODO Not important
* TODO Really important
* TODO Kind of import

So setting in the priority would look like this :

* TODO 3 Not important
* TODO 1 Really important
* TODO 2 Kind of import

And adding a new item that is more important then kind of important 
would look like this :

* TODO 4 Not important
* TODO 1 Really important
* TODO 2 More important then kind of important
* TODO 3 Kind of import

So is there any such functionality for handling priorities the anyone 
knows of? I know there is the ABC but that doesn't support what I shown 
here where I add an item in the middle of the list changes the priority 
of everything below it?

Regards,

Fredrik