ol) -> 'a list * 'b list -> ('a * 'b) option
	val filter :        ('a * 'b -> bool) -> 'a list * 'b list -> ('a * 'b) list
	val filterEq :      ('a * 'b -> bool) -> 'a list * 'b list -> ('a * 'b) list

	val appi :          (int * 'a * 'b -> unit) -> 'a list * 'b list -> unit
	val appiEq :        (int * 'a * 'b -> unit) -> 'a list * 'b list -> unit
	val appri :         (int * 'a * 'b -> unit) -> 'a list * 'b list -> unit
	val appriEq :       (int * 'a * 'b -> unit) -> 'a list * 'b list -> unit
	val mapi :   