如何打开seq >或以另一种方式使Seq.collect（fun x-> x）

dashboard.Grid
|> Seq.mapi ^-^ fun y sx -> 
    sx  |> Seq.mapi ^-^ fun x s -> 
        if not <| s.IsEmpty && s.CellState.Color = color then 
            let psteps = s.CellState.motion( dashboard, new SPosition(x,y), color )
            if psteps <> null then
                if psteps.IsEmpty then
                    Some(psteps)
                else
                    None
            else None
        else None
    |> Seq.choose id
|> Seq.collect(fun x -> x)
|> Seq.collect(fun x -> x)