ligo/test/contracts/tez_add_sub.tz

parameter (pair tez tez);
storage unit;
return (pair tez tez);
code {CAR; DUP; DUP; CAR; DIP{CDR}; ADD;
      DIP{DUP; CAR; DIP{CDR}; SUB};
      PAIR; UNIT; SWAP; PAIR};