| Expr_mul of whenexpr * whenexpr (** arithmetic multiplication *)
| Expr_div of whenexpr * whenexpr (** arithmetic division *)
| Expr_mod of whenexpr * whenexpr (** arithmetic modulo *)
| Expr_mul of whenexpr * whenexpr (** arithmetic multiplication *)
| Expr_div of whenexpr * whenexpr (** arithmetic division *)
| Expr_mod of whenexpr * whenexpr (** arithmetic modulo *)