Core impl [Graph Role + base identification]

[mdrazak2001]

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[ankurankan]

@mdrazak2001 Sorry for the delay on the end-to-end example. A simple end-to-end example could be a DAG: X -> Y X <- U -> Y with exposure X and outcome Y. The identify method should assign U as the adjustment role.

We can create a similar example in the case of a PDAG by adding another node Z: Z--X -> Y X<- U -> Y. Here, as well with X as the exposure and Y as the outcome, the identify method should assign U as the adjustment role.

let mut dag = RustDAG::new();
dag.add_edges_from([("X".to_string(), "Y".to_string()),
                                        ("U".to_string(), "X".to_string()),
                                        ("U".to_string(), "Y".to_string())]);
dag = dag.with_role("exposure".to_string(), "X".to_string());
dag = dag.with_role("outcome".to_string(), "Y".to_string());

let identification = BackdoorIdentification::new();
let dag_with_roles = identification.identify(dag)

// Similarly for the PDAG case.
let pdag_with_roles = identification.identify(pdag)

dag_with_roles.get_role_dict()
// this should have U as adjustment.