code: def test_span_computes_span_correctly(self, regions, expected_span):
      for permutation in itertools.permutations(regions, len(regions)):
          self.assertEqual(expected_span, ranges.span(permutation))
  
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 mock
  from third_party.nucleus.protos import position_pb2
  from third_party.nucleus.protos import reference_pb2
  from third_party.nucleus.protos import variants_pb2
  from third_party.nucleus.testing import test_utils
  from third_party.nucleus.util import ranges
label_desc: Use image node_id 39 for calling the RangesTests obj's underlying member method code with example usage: obj.test_span_computes_span_correctly(regions, expected_span) without return types