code: def test_params(self):
      # no params
      self.assertEqual(len(self.av.params), 0)
  
imports: import unittest
  import chainer
  import chainer.functions
  from chainer import testing
  import numpy
  from chainerrl import action_value
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