code: def test_returns_digraph_object(es):
      graph = es.plot()
  
      assert isinstance(graph, graphviz.Digraph)
  
file_path: featuretools/featuretools/tests/entityset_tests/test_plotting.py
imports: import os
  import re
  import graphviz
  import pandas
  import pytest
  from featuretools import EntitySet
  from featuretools.utils.gen_utils import Library
label_desc: Use image node_id 5 for calling a global function with example usage: test_returns_digraph_object(es) without return types