Node Group Iteration Option

It would be awesome to have an iteration option on a node group when the inputs and outputs match. That would substitute constructs like this:

also seen in the settlers project here: cloud.blender.org/p/settlers/5eda01fd5369947b4e1df9be

I would imagine it working like just an option on the node group node with the label "Iteration" that's only shown if the inputs and outputs of the group match. It would not have an input socket. In the background the option would just duplicate the node groups like shown (it may be possible to optimize performance when using the iteration value instead of just duplicating naivly).