def tracked(group_name = nil)
      ret_val = merge_super_states group_name
      ret_val.merge groups[group_name].tracked unless groups[group_name].nil?
      ret_val.subtract undefined
    end
def tracked(group_name = nil)
      ret_val = merge_super_states group_name
      ret_val.merge groups[group_name].tracked unless groups[group_name].nil?
      ret_val.subtract undefined
    end
call-seq:
   tracked(group_name = nil) => set

 Returns a set containing the currently tracked methods for a +group_name+.