…annot access `$$` in the rule

For example, if `printf("pair odd even:% d\n," $1); `was unable to access the pair side of` $$`with` $1`, fix this:
```
%rule pair(X, Y): X Y
  {
    $$ = $1 + $2;
    printf("(%d, %d)\n", $1, $2);
  }
  ;

stmt: pair(ODD, EVEN) <num> { printf("pair odd even: %d\n", $1); }
```