old_contents: from unittest import TestCase
  
  from versions.compat import basestring
  
  
  class TestBaseString(TestCase):
  
      def test(self):
          self.assertTrue(isinstance('foo', basestring))
          self.assertTrue(isinstance(u'foo', basestring))
          self.assertFalse(isinstance(42, basestring))
  
new_contents: import sys
  from unittest import TestCase
  
  from versions.compat import basestring
  
  
  class TestBaseString(TestCase):
  
      def test(self):
          self.assertTrue(isinstance('foo', basestring))
          self.assertFalse(isinstance(42, basestring))
  
          if sys.version_info[0] == 2:
              self.assertTrue(isinstance(u'foo', basestring))
  
subject: fix tests for python 3