code: def test_per_dim_mean_var_norm():
      mean = np.asarray([2.0], dtype=np.float32)
      inv_stddev = np.asarray([0.5], dtype=np.float32)
      x = C.input_variable((1,))
      func = C.per_dim_mean_variance_normalize(x, mean, inv_stddev)
      result = func.eval(
          {x: np.asarray([[3.0], [1.0]], dtype=np.float32)}
      )
      assert np.array_equal(result, [[0.5], [-0.5]])
  
imports: from __future__ import division
  import numpy
  import pytest
  import cntk
  from .ops_test_utils import unittest_helper, _test_unary_op, _test_binary_op, AA, precision, PRECISION_TO_TYPE, cntk_device
  from cntk.internal import sanitize_dtype_cntk
  from cntk.internal.utils import _ones_like, eval
label_desc: Use image node_id 17 for calling a global function with example usage: test_per_dim_mean_var_norm() without return types