let rec dfs toIn toOut toCheckEntry getAdjVerteciesOrder acc start gr =
        let nextInner acc = function
            | [] ->  acc
            | (v, w) : tl where toCheckEntry start v w acc ->
                nextInner
                <| dfs toIn toOut toCheckEntry getAdjVerteciesOrder acc v gr
                <| tl
            | _ -> acc
        let pastInAcc = toIn start acc
        let pastAdjVerteciesAcc =
            getAdjVerteciesOrder start pastInAcc gr
            |> nextInner pastInAcc
        let pastOutAcc = toOut start pastChildrenAcc
        pastOutAcc