code: def forward_chainer(self, inputs):
      x, gamma, beta = inputs
  
      running_mean = self.running_mean.copy()
      running_var = self.running_var.copy()
  
      y = chainer.functions.batch_normalization(
          x,
          gamma,
          beta,
          running_mean=running_mean,
          running_var=running_var,
          **self.optional_args,
      )
  
      # Record running values for later checks.
      self.running_mean_ch = running_mean
      self.running_var_ch = running_var
  
      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 4 for calling the TestBatchNorm obj's underlying member method code with example usage: obj.forward_chainer(inputs) and returns: y