code: def forward_chainerx(self, inputs):
      x, gamma, beta, mean, var = inputs
  
      y = chainerx.fixed_batch_norm(
          x, gamma, beta, mean=mean, var=var, **self.optional_args
      )
      return (y,)
  
imports: import unittest
  import chainer
  import numpy
  import pytest
  import chainerx
  import chainerx.testing
  from chainerx_tests import array_utils
  from chainerx_tests import op_utils
label_desc: Use image node_id 3 for calling the TestFixedBatchNorm obj's underlying member method code with example usage: obj.forward_chainerx(inputs) and returns: y