prop_delete :: BagTest Int bag => bag Int -> Int -> bag Int -> Bool
prop_delete bag x xs =
    let del_x_xs = delete x xs
     in si del_x_xs
        &&
        toOrdList del_x_xs == List.delete x (toOrdList xs)
prop_delete :: BagTest Int bag => bag Int -> Int -> bag Int -> Bool
prop_delete bag x xs =
    let del_x_xs = delete x xs
     in si del_x_xs
        &&
        toOrdList del_x_xs == List.delete x (toOrdList xs)
prop_delete bag x xs =
    let del_x_xs = delete x xs
     in si del_x_xs
        &&
        toOrdList del_x_xs == List.delete x (toOrdList xs)