code: def test_save(self):
      agent = TestAgent(self.alg)
      save_path1 = "model_dir"
      save_path2 = os.path.join("my_model", "model-2_dir")
      agent.save(save_path1)
      agent.save(save_path2)
      self.assertTrue(os.path.exists(save_path1 + "/predict_program"))
      self.assertTrue(os.path.exists(save_path1 + "/learn_program"))
      self.assertTrue(os.path.exists(save_path2 + "/predict_program"))
      self.assertTrue(os.path.exists(save_path2 + "/learn_program"))
  
imports: import numpy
  import unittest
  from paddle import fluid
  from parl import layers
  import parl
  import os
label_desc: Use image node_id 3 for calling the AgentBaseTest obj's underlying member method code with example usage: obj.test_save() without return types