OpExp.Op.MINUS, new NumExp(1))))), new OpExp(
new NumExp(10), OpExp.Op.TIMES, new IdExp("a")))),
new PrintStm(new LastExpList(new IdExp("b")))));
System.out.println("First prog:");
prog.interpret();
System.out.println();
prog = new PrintStm(new PairExpList(new IdExp("a"),
new LastExpList(new EseqExp(new PrintStm(new PairExpList(
new IdExp("c"), new PairExpList(new IdExp("d"),