code: def ref_weight_standardization(w, channel_axis, eps, output_stat):
      channel_axis = channel_axis + w.ndim * (channel_axis < 0)
  
      axes = tuple(_get_axes_excluding(len(w.shape), channel_axis))
  
      w_mean = w.mean(axis=axes, keepdims=True)
      w_var = w.var(axis=axes, keepdims=True)
  
      norm = (w - w_mean) / (w_var + eps) ** 0.5
  
      if output_stat:
          return norm, w_mean, w_var
  
      return norm
  
file_path: nnabla/python/test/function/test_weight_standardization.py
imports: import pytest
  import numpy
  import nnabla
  import nnabla.functions
  import nnabla.parametric_functions
  from nnabla.testing import assert_allclose
  from nbla_test_utils import list_context
  from nnabla.normalization_functions import _get_axes_excluding
label_desc: Use image node_id 2 for calling a global function with example usage: ref_weight_standardization(w, channel_axis, eps, output_stat) and returns: norm, norm,  w_mean,  w_var