Comparable.With_zeromodule T : sig ... endval validate_positive : T.t Validate.checkval validate_non_negative : T.t Validate.checkval validate_negative : T.t Validate.checkval validate_non_positive : T.t Validate.checkval is_positive : T.t -> boolval is_non_negative : T.t -> boolval is_negative : T.t -> boolval is_non_positive : T.t -> boolval sign : T.t -> Base__Sign0.tReturns Neg, Zero, or Pos in a way consistent with the above functions.