In Drupal 7, I would like to set up a rule that sends an email to all users in an ORGANIC GROUPS Role, based on an action. I know how to get the action, I know how to do the loop, I know how to send the email.

I cannot, for the life of me, figure out how to get a list of group members with group role "X". 

PS - I've reviewed this link: <http://www.sthlmconnection.se/en/blog/rules-based-notifications-organic-groups> , and it's for D6.