let l = [1;2;3;4;5] ;;
let rec mem
list element
= match list with | [] -> false
| head :: _ when head = element -> true
| _ :: tail -> mem tail element
;;
Printf.printf
"%B \n" (mem l
3)
bGV0IGwgPSBbMTsyOzM7NDs1XSA7OwoKbGV0IHJlYyBtZW0gbGlzdCBlbGVtZW50ID0gbWF0Y2ggbGlzdCB3aXRoIAoJfCBbXSAtPiBmYWxzZQoJfCBoZWFkIDo6IF8gd2hlbiBoZWFkID0gZWxlbWVudCAtPiB0cnVlCgl8IF8gOjogdGFpbCAtPiBtZW0gdGFpbCBlbGVtZW50Cjs7CgpQcmludGYucHJpbnRmICIlQiBcbiIgKG1lbSBsIDMpCgo=