Read an integer from the user
Inheritance: Statement
 public virtual void Visit(Read node)
 {
 }
 void ReadStmt(out Statement stmt)
 {
     stmt = null;
     Expect(15);
     if (la.kind == 1) {
     Get();
     stmt = new Read(new Variable(t.val));
     } else if (la.kind == 6) {
     Get();
     Expect(1);
     stmt = new Read(new Variable(t.val));
     Expect(9);
     } else SynErr(55);
 }