code: def test_unigram(self):
      valid, test = testing_utils.train_model(
          {
              "model": "test_agents/unigram",
              "task": "integration_tests",
              "num_epochs": 1.0,
              "batchsize": 32,
              "truncate": 4,
          }
      )
      assert valid["f1"] > 0
  
imports: import unittest
  import parlai.utils.testing
label_desc: Use image node_id 1 for calling the TestUnigramTorchAgent obj's underlying member method code with example usage: obj.test_unigram() without return types