Add 'role' data attribute. Note, that 'role' attribute is a part of reach ARIA API described here: http://www.w3.org/TR/wai-aria/ Among 'role', it defines lots of aria-* attributes

fun f (x : int * float) : string = x
fun g (x : int * float * bool) : string = x
fun h (x : {A : int, B : float, C : bool}) : string = x