class TestRegexp(unittest.TestCase):

              def test_simple_regexp(self):
                  result = re.search(r'a.*c', 'abc')
                  self.assertIsNotNone(result)
                  self.assertEqual(result.group(), 'abc')
                  self.assertEqual(result.group(0), 'abc')
                  with self.assertRaises(IndexError):
                      result.group(1)
                  self.assertEqual(result.groups(), ())
        

          @listify
          def flatten(items):
              """Flatten an iterable and return it as a flat list"""
              for item in items:
                  if isinstance(item, str):
                      yield item
                  elif hasattr(item, '__iter__'):
                      for elem in flatten(item):
                          yield elem
                      else:
                          yield item