{"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"assert_eq!(relation.parents(\"0\"),"}]}
    assert_eq!(relation.parents("0"), vec!["2"]);
    assert_eq!(relation.minimal_upper_bounds("0", "3"), vec!["2"]);
    assert_eq!(relation.parents("2"), vec!["1"]);