code: def make_q_func(self, env):
      obs_size = env.observation_space.low.size
      hidden_size = 64
      return iqn.ImplicitQuantileQFunction(
          psi=chainerrl.links.Sequence(
              L.Linear(obs_size, hidden_size),
              F.relu,
          ),
          phi=chainerrl.links.Sequence(
              chainerrl.agents.iqn.CosineBasisLinear(32, hidden_size),
              F.relu,
          ),
          f=L.Linear(hidden_size, env.action_space.n),
      )
  
imports: import unittest
  import numpy
  import chainer
  import chainer.functions
  import chainer.links
  from chainer import testing
  import basetest_dqn_like
  from basetest_training import _TestBatchTrainingMixin
  import chainerrl
  from chainerrl.agents import iqn
label_desc: Use image node_id 1 for calling the TestIQNOnDiscreteABC obj's underlying member method code with example usage: obj.make_q_func(env) and returns: iqn