code: def test_empty(self):
      graph, args, out = dot.to_graph(lambda: None)()
      self.assertEmpty(args)
      self.assertIsNone(out)
      self.assertEmpty(graph.nodes)
      self.assertEmpty(graph.edges)
      self.assertEmpty(graph.subgraphs)
  
imports: from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import dot
  from haiku._src import module
  from haiku._src import test_utils
  import jax
  import jax.numpy
label_desc: Use image node_id 1 for calling the DotTest obj's underlying member method code with example usage: obj.test_empty() without return types