code: def test_invalid_num_fields(self, invalid_num_fields):
      bed_path = test_utils.genomics_core_testdata("test_regions.bed")
      with self.assertRaisesRegexp(
          ValueError, "Invalid requested number of fie"
      ):
          _ = bed.BedReader(bed_path, num_fields=invalid_num_fields)
  
file_path: deepvariant/third_party/nucleus/io/bed_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from absl.testing import absltest
  from absl.testing import parameterized
  from third_party.nucleus.io import bed
  from third_party.nucleus.io.python import bed_reader
  from third_party.nucleus.protos import bed_pb2
  from third_party.nucleus.testing import test_utils
label_desc: Use image node_id 4 for calling the BedReaderTests obj's underlying member method code with example usage: obj.test_invalid_num_fields(invalid_num_fields) without return types