/* set input vars */
    char *string = . . .
    Set_Global("validate", "QUANTITY",  "i", quantity);
    Set_Global("validate", "ORDERTYPE", "s", ordertype);

    /* run code string */
    status = Run_Codestr(PY_STATEMENT, 
                         string, "validate", "", NULL);
    if (status == -1)
        PyErr_Print();  /* stack traceback */
    else {
        /* fetch output vars */
        Get_Global("validate", "QUANTITY", "i", &quantity);
        Get_Global("validate", "MESSAGES", "s", &messages);
    }