class_docstr: Test io.SamReader on CRAM formatted files.
code: def test_iterate(self, filename, has_embedded_ref):
      with self._make_reader(filename, has_embedded_ref) as reader:
          reads = list(reader.iterate())
          self.assertEqual(len(reads), 3)
          self.assertEqual(
              [read.fragment_name for read in reads],
              ["cram1", "cram2", "cram3"],
          )
          self.assertEqual(
              [read.aligned_sequence for read in reads],
              [
                  "CCCTAACCCTAACCCTAACCCTAACCCTANNNNNN",
                  (
                      "TAACCCTAACCCTAACCCTAACCCTAACCCTAACCCTAACCAAAACGAATCAAAAAAGAAAAACGAA"
                      "AAAAAAA"
                  ),
                  "CACAGACGCTT",
              ],
          )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import itertools
  from absl.testing import absltest
  from absl.testing import parameterized
  import six
  from etils import epath
  from third_party.nucleus.io import sam
  from third_party.nucleus.io import tfrecord
  from third_party.nucleus.protos import reads_pb2
  from third_party.nucleus.protos import reference_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 3 for calling the CramReaderTests obj's underlying member method code with example usage: obj.test_iterate(filename, has_embedded_ref) without return types