@Test
public void benzene() 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("c1ccccc1"));
}