code: def test_blockgrad():
      a = mx.sym.Variable("a")
      b = mx.sym.BlockGrad(2 * a)
      exe = b._simple_bind(ctx=mx.cpu(), a=(10, 10))
  
imports: import copy
  import sys
  import os
  import logging
  import re
  import json
  import mxnet
  import numpy
  from common import assertRaises, models, TemporaryDirectory
  from mxnet.base import NotImplementedForSymbol
  from mxnet.test_utils import discard_stderr, rand_shape_nd, use_np, environment
  from mxnet.util import np_shape
  import pickle
label_desc: Use image node_id 14 for calling a global function with example usage: test_blockgrad() without return types