{"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"assert_eq!(d.immediate_dominator(1),"}]}
    assert_eq!(d.immediate_dominator(1), Some(6));
    assert_eq!(d.immediate_dominator(0), None); // <-- note that 0 is not in graph
    assert_eq!(d.immediate_dominator(2), Some(6));