let adjacentStates = List.map (fun x ->
                                            let containsX list = List.exists (fun (b,g,f) -> b = x) list
                                            if (not (List.exists (fun elem -> elem = x) CS)) && (not (containsX removedCurrent))
                                                then
                                                    let newGS = GS + 1
                                                    let newFS = newGS + totalManhattanDistance x goal
                                                    Some(x, newGS, newFS)
                                                else None) adjacentBoards
            let newCS = currentBoard::CS
            let newOS = List.sortBy (fun (b,g,f) -> f) (List.append removedCurrent adjacentStates) //problem here is it affects the type here and i get an error