let add_constants cs1 cs2 = let m = MConst.fold add_constant cs2 cs1 in if MConst.is_empty m then let c0 = if is_int_const (fst (MConst.choose cs1)) then ConstInt (Num.Int 0) else ConstReal (Num.Int 0) in MConst.add c0 1 m else m