enum intstack_error {
	INTSTACK_OK = 0,
	INTSTACK_OVERFLOW = 1,
	INTSTACK_UNDERFLOW = 2
};

struct pop_result {
    int data;
    int error;
};

program INTSTACK_PROG { 
   version INTSTACK_VERSION {
       intstack_error	PUSH(int)  = 11 ;
       pop_result	POP(void)  = 12 ;
   } = 1 ;
} = 0x20051002 ;