@Test
public void benzeneMixed() throws Exception {

    Graph g = Parser.parse("C:1:C:C:C:C:C1");
    Assert.assertThat(Generator.generate(g),
                      CoreMatchers.is("C:1:C:C:C:C:C1"));
    Assert.assertThat(Generator.generate(f.apply(g)),
                      CoreMatchers.is("C:1:C:C:C:C:C1"));
}