Ak.pivottable

Ok, so with this the titanic example becomes:

    let data =
      titanic()
        |> Frame.pivotTable (fun r -> r.GetAs<string>("Sex")) (fun r -> r.GetAs<string>("Survived")) Frame.countRows
        |> Frame.indexColsWith ["Died"; "Survived"]

    data?total <- data |> Frame.transpose |> Frame.sum 

    data?Died / data?total

etc ...