`module IdSet = CFG.Node.IdSet`
`type t````=` `{`

`node : CFG.Node.t;` | (** node whose instructions will be analyzed *)
`visited_preds : IdSet.t;` | (** predecessors of `node` we have already visited in current iter *)
`priority : int;` | (** |preds| - |visited preds|. *)

`}```
`val node : t ‑> CFG.Node.t`
`val visited_preds : t ‑> IdSet.elt list`
`val priority : t ‑> int`
`val compute_priority : CFG.t ‑> CFG.Node.t ‑> IdSet.t ‑> int`
`val make : CFG.t ‑> CFG.Node.t ‑> t`
`val add_visited_pred : CFG.t ‑> t ‑> IdSet.elt ‑> t`

add `node_id` to the visited preds for `t`