code: def test_groupnorm():
      ctx = mx.context.current_context()
      x = mx.nd.random.uniform(1, 2, (4, 16, 8, 8), ctx=ctx)
      gn = GroupNorm(4, 16)
      gn.initialize(ctx=ctx)
      y = gn(x)
      y = y.reshape(0, 4, -1)
      print("y.mean(2) =", y.mean(2))
      mx.test_utils.assert_almost_equal(
          y.mean(2).asnumpy(),
          mx.nd.zeros_like(y.mean(2)).asnumpy(),
          rtol=1e-3,
          atol=1e-3,
      )
  
label_desc: Use image node_id 1 for calling a global function with example usage: test_groupnorm() without return types