code: def test_correct_pipeline_encoder_imputer_validation():
      """
      Validate correct unimodal pipeline. Both encoding and imputation operations
      take right places in the pipeline.
      """
      first_source = PipelineNode("data_source_table")
      second_imputer = PipelineNode(
          "simple_imputation", nodes_from=[first_source]
      )
      third_encoder = PipelineNode(
          "one_hot_encoding", nodes_from=[second_imputer]
      )
      fourth_imputer = PipelineNode(
          "simple_imputation", nodes_from=[third_encoder]
      )
      root = PipelineNode("linear", nodes_from=[fourth_imputer])
      pipeline = Pipeline(root)
  
      encoding_correct = (
          PipelineStructureExplorer().check_structure_by_tag(
              pipeline, tag_to_check="encoding"
          )
      )
      imputer_correct = (
          PipelineStructureExplorer().check_structure_by_tag(
              pipeline, tag_to_check="imputation"
          )
      )
  
      assert encoding_correct is True
      assert imputer_correct is True
  
imports: from fedot.core.pipelines.node import PipelineNode
  from fedot.core.pipelines.pipeline import Pipeline
  from fedot.preprocessing.structure import PipelineStructureExplorer
label_desc: Use image node_id 1 for calling a global function with example usage: test_correct_pipeline_encoder_imputer_validation() without return types