code: def make_ifar_plot(workflow, trigger_file, out_dir, tags=None,
                     hierarchical_level=None):
      
  
      if hierarchical_level is not None and tags:
          tags = [("HIERARCHICAL_LEVEL_{:02d}".format(
                  hierarchical_level))] + tags
      elif hierarchical_level is not None and not tags:
          tags = ["HIERARCHICAL_LEVEL_{:02d}".format(hierarchical_level)]
      elif hierarchical_level is None and not tags:
          tags = []
  
      makedir(out_dir)
      node = PlotExecutable(workflow.cp, 'page_ifar', ifos=workflow.ifos,
                      out_dir=out_dir, tags=tags).create_node()
      node.add_input_opt('--trigger-file', trigger_file)
      if hierarchical_level is not None:
          node.add_opt('--use-hierarchical-level', hierarchical_level)
      node.new_output_file_opt(workflow.analysis_time, '.png', '--output-file')
      workflow += node
      return node.output_files[0]
docs: Creates a node in the workflow for plotting cumulative histogram
      of IFAR values.