class_docstr: Tests for `plugin_util.experiment_id`.
code: def test_present(self):
      environ = {experiment_id.WSGI_ENVIRON_KEY: "123"}
      self.assertEqual(plugin_util.experiment_id(environ), "123")
  
imports: import textwrap
  from tensorboard import context
  from tensorboard import plugin_util
  from tensorboard import test
  from tensorboard.backend import experiment_id
label_desc: Use image node_id 2 for calling the ExperimentIdTest obj's underlying member method code with example usage: obj.test_present() without return types