code: def control_group(self, control_group_id, ctrl, shift, alt):
      
      action = sc_pb.Action()
      select = action.action_ui.control_group
  
      mod = sc_ui.ActionControlGroup
      if not ctrl and not shift and not alt:
        select.action = mod.Recall
      elif ctrl and not shift and not alt:
        select.action = mod.Set
      elif not ctrl and shift and not alt:
        select.action = mod.Append
      elif not ctrl and not shift and alt:
        select.action = mod.SetAndSteal
      elif not ctrl and shift and alt:
        select.action = mod.AppendAndSteal
      else:
        return  # unknown
      select.control_group_index = control_group_id
      return action
docs: Act on a control group, selecting, setting, etc.