code: def test_postproc_opt_nodes():
      """
      Test to check if the postproc_nodes method correctly process OptNodes
      The method should skip OptNodes without changing their type
  
      postproc_nodes method is called at the end of the update_node method
      """
      pipeline = get_pipeline()
  
      lda_node = pipeline.nodes[-2]
      qda_node = pipeline.nodes[-1]
  
      pipeline.connect_nodes(lda_node, qda_node)
  
      # Check that the postproc_nodes method does not change the type of OptNode type nodes
      new_node = OptNode({"name": "opt"})
      pipeline.update_node(old_node=lda_node, new_node=new_node)
      opt_node = pipeline.nodes[3]
      assert isinstance(opt_node, OptNode)
  
imports: from fedot.core.pipelines.node import PipelineNode
  from fedot.core.pipelines.pipeline import Pipeline
  from golem.core.optimisers.graph import OptNode
label_desc: Use image node_id 3 for calling a global function with example usage: test_postproc_opt_nodes() without return types