code: def ref_norm_normalization(x, p, axis, eps=1e-12):
      if p is None:
          p = 2.0
      # calculate norm
      y = x
      y = np.abs(y)
      y = np.power(y, p)
      y = np.sum(y, axis, keepdims=True) + eps
      y = np.power(y, 1.0 / p)
      # normalization
      y = x / y
      return y
  
imports: import pytest
  import numpy
  import nnabla.functions
  from nbla_test_utils import list_context
label_desc: Use image node_id 1 for calling a global function with example usage: ref_norm_normalization(x, p, axis, eps) and returns: y