code: def test_is_valid(self, region, expected):
      self.assertEqual(self.in_mem.is_valid(region), expected)
      self.assertEqual(self.fasta_reader.is_valid(region), expected)
  
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
  import six
  from third_party.nucleus.io import fasta
  from third_party.nucleus.io.python import reference
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 8 for calling the InMemoryFastaReaderTests obj's underlying member method code with example usage: obj.test_is_valid(region, expected) without return types