ceiling ket take the ceiling function of the value in the ket label while preserving the ket label category if the value is not a number, then return the ket unchanged also, we preserve the ket coefficient
-- ceiling of a simple number: ceiling |2.7> |3> -- ceiling of a number with a category, in this case "number" ceiling |number: 5.3> |number: 6> -- attempted ceiling of a non number: ceiling |alpha> |alpha>