code: def test_op_reduce_mean_all_constant(
      input_data, axis, device_id, precision
  ):
      dt = PRECISION_TO_TYPE[precision]
      value = AA(input_data, dtype=dt)
      from .. import reduce_mean
      from cntk import Axis, Constant
  
      a = Constant(value, name="a")
      input_op = reduce_mean(a, axis=Axis.all_axes())
      expected_forward = AA(np.mean(value))
      actual_forward = input_op.eval()
      assert np.allclose(actual_forward, expected_forward)
  
imports: from __future__ import division
  import numpy
  import itertools
  import pytest
  import cntk
  from .ops_test_utils import unittest_helper, _test_unary_op, AA, precision, PRECISION_TO_TYPE, constant
  from cntk.internal import sanitize_dtype_cntk
  from ..None import reduce_sum, reduce_max, reduce_min, reduce_mean, reduce_log_sum_exp, reduce_prod
label_desc: Use image node_id 8 for calling a global function with example usage: test_op_reduce_mean_all_constant(input_data, axis, device_id, precision) without return types