let rec removeDups xs =
match xs with
| h :: k :: t when h = k -> removeDups (h :: t)
| h :: t -> h :: removeDups t
| [] -> []
do
printfn "%A" <| removeDups [1; 2; 2; 3]
bGV0IHJlYyByZW1vdmVEdXBzIHhzID0KICAgIG1hdGNoIHhzIHdpdGgKICAgIHwgaCA6OiBrIDo6IHQgd2hlbiBoID0gayAtPiByZW1vdmVEdXBzIChoIDo6IHQpCiAgICB8IGggOjogdCAgICAgICAgICAgICAgICAgLT4gaCA6OiByZW1vdmVEdXBzIHQKICAgIHwgW10gICAgICAgICAgICAgICAgICAgICAtPiBbXQoKZG8KICAgcHJpbnRmbiAiJUEiIDx8ICByZW1vdmVEdXBzICBbMTsgMjsgMjsgM10=