code: def test_custom_pad_none(self):
      np.testing.assert_raises_regex(
          ValueError,
          "Invalid custom_pad",
          aggregated_pad,
          pad_type="custom",
          kernel_shape=(1, 2, 3),  # doesn't matter
          custom_pad=None,
      )
  
imports: import itertools
  import numpy
  import pytest
  from coremltools.converters.mil.mil.ops.defs._utils import aggregated_pad, effective_kernel, pack_elements_into_bits, restore_elements_from_packed_bits, spatial_dimensions_out_shape
label_desc: Use image node_id 4 for calling the TestAggregatePadding obj's underlying member method code with example usage: obj.test_custom_pad_none() without return types