@Test public void resonate() throws Exception {

    // two different resonance forms with the same
    // ordering
    Graph g = Graph.fromSmiles("C1=CC2=CC=CC2=C1");
    Graph h = Graph.fromSmiles("C=1C=C2C=CC=C2C=1");
    // produce different SMILES
    assertThat(g.toSmiles(), is("C1=CC2=CC=CC2=C1"));
    assertThat(h.toSmiles(), is("C=1C=C2C=CC=C2C1"));
    // but once resonate we get the same SMILES 
    assertThat(g.resonate().toSmiles(), is(h.resonate().toSmiles()));
}