code: def categorical_loss(y, t):
      return -t * np.log(np.clip(y, 1e-10, 1.0))
  
imports: import unittest
  import chainer
  import chainer.links
  from chainer import testing
  import numpy
  import basetest_dqn_like
  from basetest_training import _TestBatchTrainingMixin
  import chainerrl
  from chainerrl.agents import categorical_dqn
  from chainerrl.agents.categorical_dqn import compute_value_loss
  from chainerrl.agents.categorical_dqn import compute_weighted_value_loss
  from chainerrl.agents import CategoricalDQN
label_desc: Use image node_id 4 for calling a global function with example usage: categorical_loss(y, t) and returns: unknown