Singleflag

This module makes a flag only usable on one node (for each user). Think of having a node flagged as a "default."

I originally wrote the module because there are so many good modules that use the Flag module's API, and I needed a way for users to "set a default research point."

The module may not be production-ready, so please look over the code before implementing it.

Note: I'm posting this project long after I wrote the code, which is provided mainly for reference purposes. I've undoubtedly learned better ways to do things in Drupal/PHP since writing this code, but I do not intend to update/modify this code unless I have specific requests to do so.