code: def test_bf16_activation():
      data_sym_fp32 = mx.sym.Variable(name="data")
      data_sym_bf16 = mx.sym.Variable(name="data", dtype="bfloat16")
  
      dshapes = [(3, 16), (3, 16, 16), (3, 3, 16, 16)]
      act_types = ["relu", "sigmoid", "tanh"]
      for data_shape, act_type in itertools.product(dshapes, act_types):
          act_fp32 = mx.sym.Activation(data_sym_fp32, act_type=act_type)
          act_bf16 = mx.sym.Activation(data_sym_bf16, act_type=act_type)
  
          check_operator_accuracy(
              act_fp32, act_bf16, data_shape, bf16_use_fp32_params=True
          )
  
imports: import os
  import sys
  import mxnet
  import numpy
  from random import randint
  import itertools
  from mxnet.test_utils import assert_almost_equal_with_err, rand_shape_nd
  import pytest
label_desc: Use image node_id 6 for calling a global function with example usage: test_bf16_activation() without return types