code: def test_self_reference():
      hist_list = ["date:A_score", "date:A_score:num_employees"]
  
      pipeline = Pipeline(
          modules=[
              JsonReader(
                  file_path=resources.data("example_histogram.json"),
                  store_key="hists",
              ),
              SelfReference(
                  hists_key="hists",
                  settings=Settings(features=hist_list),
              ),
          ]
      )
      pipeline.transform(datastore={})
  
file_path: popmon/tests/popmon/pipeline/test_report_pipelines.py
imports: from popmon import resources
  from popmon.base import Pipeline
  from popmon.config import Settings
  from popmon.io import JsonReader
  from popmon.pipeline.report_pipelines import ExpandingReference, ExternalReference, RollingReference, SelfReference
label_desc: Use image node_id 1 for calling a global function with example usage: test_self_reference() without return types