code: def test_pack_basic_2(self):
      original_data = np.array([1, 2, 3, 4, 5], dtype=np.int8)
      expected_packed_data = np.array([33, 67, 5], dtype=np.uint8)
      packed_data = pack_elements_into_bits(original_data, nbits=4)
      np.testing.assert_array_equal(packed_data, expected_packed_data)
  
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 2 for calling the TestPackUnpackBits obj's underlying member method code with example usage: obj.test_pack_basic_2() without return types