How to generate spheres in first trigger, and cube in second trigger

How to generate spheres in first trigger, and cube in second trigger?
How to use rep.modify.register API?
The Scenario I met was I want to delete the specific replicatorItem and generate a new one in different trigger, Thanks!!

  def randomize_spheres():
      spheres = rep.create.sphere(
          position= rep.distribution.uniform((0,0,0), (2, 2, 2)),
          scale=0.1,
          count=2)
      return spheres.node
  rep.randomizer.register(randomize_spheres)

  def randomize_cube():
      cube = rep.create.cube(
          position= rep.distribution.uniform((0,0,0), (2, 2, 2)),
          scale=0.1,
          count=2)
      return cube.node
  rep.randomizer.register(randomize_cube)


  with rep.trigger.on_time(num=2,interval=5): 
      with camera:
          rep.modify.pose(
              position = (2, 2, 50),
              scale = (1, 1, 1),
          )
      spheres = rep.randomizer.randomize_spheres()
      with spheres:
          rep.modify.pose(
              rotation = rep.distribution.uniform((0,0,0), (2, 2, 2)),
          )
      # rep.modify.register(
      #     randomize_cube,
      # override=True)