code: def test_node_ordering():
      example_graph = {
          "a": ["b", "c", "d"],
          "b": [],
          "c": ["d"],
          "d": [],
          "e": ["f"],
          "f": [],
      }
      sorted_nodes, removed_edges = StoryGraph.topological_sort(
          example_graph
      )
      # sorting removed_edges converting set converting it to list
      assert removed_edges == list()
      check_graph_is_sorted(example_graph, sorted_nodes, removed_edges)
  
file_path: rasa/tests/shared/core/training_data/test_graph.py
imports: from rasa.shared.core.training_data.structures import StoryGraph
  import rasa.shared.core.training_data.loading
  from rasa.shared.core.domain import Domain
label_desc: Use image node_id 2 for calling a global function with example usage: test_node_ordering() without return types