docstr: Test that we can use context manager to do two queries in sequence.
docstr_tok: ["Test","that","we","can","use","context","manager","to","do","two","queries","in","sequence","."]
code: def test_context_manager(self):
      """Test that we can use context manager to do two queries in sequence."""
      reader = sam_reader.SamReader.from_file(
          reads_path=self.bam, ref_path="", options=self.options
      )
      region = ranges.parse_literal("chr20:10,000,000-10,000,100")
      with reader:
          with reader.query(region) as query_iterable1:
              self.assertIsNotNone(query_iterable1)
              self.assertIsInstance(
                  query_iterable1, clif_postproc.WrappedCppIterable
              )
          with reader.query(region) as query_iterable2:
              self.assertIsNotNone(query_iterable2)
              self.assertIsInstance(
                  query_iterable2, clif_postproc.WrappedCppIterable
              )
  
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 clif_postproc
  from third_party.nucleus.io.python import sam_reader
  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 6 for calling the SamReaderTest obj's underlying member method code with example usage: obj.test_context_manager() without return types