code: def test_undefined_blob(self):
      job = example_job()
      with job:
          with Task():
              ops.Add(["a", "b"])
      with self.assertRaises(AssertionError) as e:
          net_printer.analyze(job)
      self.assertEqual("Blob undefined: a", str(e.exception))
  
file_path: pytorch/caffe2/python/net_printer_test.py
imports: from caffe2.python import net_printer
  from caffe2.python.checkpoint import Job
  from caffe2.python.net_builder import ops
  from caffe2.python.task import Task, final_output, WorkspaceType
  import unittest
label_desc: Use image node_id 3 for calling the TestNetPrinter obj's underlying member method code with example usage: obj.test_undefined_blob() without return types