code: def test_basic_dag_without_names_plot():
      @ray.remote
      def a(*args, **kwargs):
          pass
  
      tmp1 = a.bind()
      tmp2 = a.bind()
      tmp3 = a.bind(tmp1, tmp2)
      tmp4 = a.bind()
      tmp5 = a.bind(tmp4)
      tmp6 = a.bind()
      dag = a.bind(tmp3, tmp5, tmp6)
  
      with tempfile.TemporaryDirectory() as tmpdir:
          to_file = os.path.join(tmpdir, "tmp.png")
          ray.dag.plot(dag, to_file)
          assert os.path.isfile(to_file)
  
      graph = ray.dag.vis_utils._dag_to_dot(dag)
      to_string = graph.to_string()
      assert "a -> a_2" in to_string
      assert "a_1 -> a_2" in to_string
      assert "a_3 -> a_4" in to_string
      assert "a_2 -> a_6" in to_string
      assert "a_4 -> a_6" in to_string
      assert "a_5 -> a_6" in to_string
  
imports: import os
  import pytest
  import sys
  import tempfile
  import ray
label_desc: Use image node_id 2 for calling a global function with example usage: test_basic_dag_without_names_plot() without return types