def test_equals(self): self.assertEqual(vowel_2_index('this is my string'), 'th3s 6s my str15ng')
def test_equals_3(self): self.assertEqual(vowel_2_index(''), '')
def test_equals_2(self): self.assertEqual(vowel_2_index( 'Codewars is the best site in the world'), 'C2d4w6rs 10s th15 b18st s23t25 27n th32 w35rld')
def test_equals_2(self): self.assertEqual( vowel_2_index('Codewars is the best site in the world'), 'C2d4w6rs 10s th15 b18st s23t25 27n th32 w35rld')