code: def test_iterate_gff_reader(self, gff_filename):
      gff_path = test_utils.genomics_core_testdata(gff_filename)
      expected = [("ctg123", 999, 9000), ("ctg123", 999, 1012)]
  
      with gff.GffReader(gff_path) as reader:
          records = list(reader.iterate())
      self.assertLen(records, 2)
      self.assertEqual(
          [
              (r.range.reference_name, r.range.start, r.range.end)
              for r in records
          ],
          expected,
      )
  
file_path: deepvariant/third_party/nucleus/io/gff_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 gff
  from third_party.nucleus.io import tfrecord
  from third_party.nucleus.protos import gff_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 1 for calling the GffReaderTests obj's underlying member method code with example usage: obj.test_iterate_gff_reader(gff_filename) without return types