code: def test_params(self):
      # no params
      assertions.assertEqual(len(self.av.params), 0)
  
imports: import unittest
  import numpy
  import pytest
  import torch
  from pfrl import action_value
  from pfrl.testing import torch_assert_allclose
label_desc: Use image node_id 6 for calling the TestSingleActionValue obj's underlying member method code with example usage: obj.test_params() without return types