let stringify_combtest op suffix = match op with
| Ast.And -> "CTEST_AND_"^suffix
| Ast.Or -> "CTEST_OR_"^suffix
| Ast.Nand -> "CTEST_NAND_"^suffix
| Ast.Nor -> "CTEST_NOR_"^suffix
| Ast.Xor -> "CTEST_XOR_"^suffix
| Ast.Not -> raise(Failure "Unary operator")