'If dictsortreversed is passed something other than a list of
dictionaries, fail silently.'

def test_invalid_values(self):

    self.assertEqual(dictsortreversed([1, 2, 3], 'age'), '')
    self.assertEqual(dictsortreversed('Hello!', 'age'), '')
    self.assertEqual(dictsortreversed({'a': 1}, 'age'), '')
    self.assertEqual(dictsortreversed(1, 'age'), '')
