tup2Type :: (TupleType :<: t)
    => TypeRep t a -> TypeRep t b -> TypeRep t (a,b)
tup2Type = sugarSym Tup2_t
tup2Type :: (TupleType :<: t)
    => TypeRep t a -> TypeRep t b -> TypeRep t (a,b)
tup2Type = sugarSym Tup2_t
tup2Type = sugarSym Tup2_t