code: def test_remove_ref_band(self):
      pileup = _mock_pileup_array_with_reads()
      bottom_part = vis.remove_ref_band(pileup)
      self.assertEqual(
          (pileup.shape[0] - 5, pileup.shape[1]),
          bottom_part.shape,
          msg="Checking output shape is correct.",
      )
      # Since the ref band is all zero, the sum should stay the same.
      self.assertEqual(
          np.sum(pileup),
          np.sum(bottom_part),
          msg="Checking bottom part of pileup is intact.",
      )
  
      test_pileup = np.zeros((100, 200))
      self.assertEqual(
          (95, 200), vis.remove_ref_band(test_pileup).shape
      )
  
      too_small = np.zeros((4, 10)) + 254
      with self.assertRaises(AssertionError):
          vis.remove_ref_band(too_small)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import glob
  import os
  from absl.testing import absltest
  from absl.testing import parameterized
  import numpy
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import vis
  from tensorflow.core.example import example_pb2
  from tensorflow.core.example import feature_pb2
label_desc: Use image node_id 20 for calling the VisTest obj's underlying member method code with example usage: obj.test_remove_ref_band() without return types