lib/mongoid_followable/follower.rb
def follower_of?(model)
      0 < self.followees.by_model(model).limit(1).count * model.followers.by_model(self).limit(1).count
    end
def follower_of?(model)
      0 < self.followees.by_model(model).limit(1).count * model.followers.by_model(self).limit(1).count
    end
see if this model is follower of some model

 Example:
   >> @jim.follower_of?(@ruby)
   => true