public final AntlrPilarParser.rhs_return rhs() throws RecognitionException {
    AntlrPilarParser.rhs_return retval = new AntlrPilarParser.rhs_return();
    retval.start = input.LT(1);
    int rhs_StartIndex = input.index();
    Object root_0 = null;

    AntlrPilarParser.annotationList_return annotationList268 = null;

    AntlrPilarParser.exp_return exp269 = null;

    RewriteRuleSubtreeStream stream_exp = new RewriteRuleSubtreeStream(adaptor,
        "rule exp");
    RewriteRuleSubtreeStream stream_annotationList = new RewriteRuleSubtreeStream(
        adaptor, "rule annotationList");
    try {
      if (state.backtracking > 0 && alreadyParsedRule(input, 66)) {
        return retval;
      }
      // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:513:2: ( annotationList exp -> ^( RHS annotationList exp ) )
      // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:513:4: annotationList exp
      {
        pushFollow(FOLLOW_annotationList_in_rhs4820);
        annotationList268 = annotationList();

        state._fsp--;
        if (state.failed) return retval;
        if (state.backtracking == 0)
          stream_annotationList.add(annotationList268.getTree());
        pushFollow(FOLLOW_exp_in_rhs4822);
        exp269 = exp();

        state._fsp--;
        if (state.failed) return retval;
        if (state.backtracking == 0) stream_exp.add(exp269.getTree());

        // AST REWRITE
        // elements: exp, annotationList
        // token labels: 
        // rule labels: retval
        // token list labels: 
        // rule list labels: 
        // wildcard labels: 
        if (state.backtracking == 0) {
          retval.tree = root_0;
          RewriteRuleSubtreeStream stream_retval = new RewriteRuleSubtreeStream(
              adaptor, "rule retval", retval != null ? retval.tree : null);

          root_0 = (Object) adaptor.nil();
          // 513:41: -> ^( RHS annotationList exp )
          {
            // /Users/robby/Repositories/sireum-parser/sireum-parser/src/main/java/org/sireum/pilar/parser/AntlrPilar.g:513:44: ^( RHS annotationList exp )
            {
              Object root_1 = (Object) adaptor.nil();
              root_1 = (Object) adaptor.becomeRoot(
                  (Object) adaptor.create(RHS, "RHS"),
                  root_1);

              adaptor.addChild(root_1, stream_annotationList.nextTree());
              adaptor.addChild(root_1, stream_exp.nextTree());

              adaptor.addChild(root_0, root_1);
            }

          }

          retval.tree = root_0;
        }
      }

      retval.stop = input.LT(-1);

      if (state.backtracking == 0) {

        retval.tree = (Object) adaptor.rulePostProcessing(root_0);
        adaptor.setTokenBoundaries(retval.tree, retval.start, retval.stop);
      }
    } catch (RecognitionException re) {
      reportError(re);
      recover(input, re);
      retval.tree = (Object) adaptor.errorNode(
          input,
          retval.start,
          input.LT(-1),
          re);

    } finally {
      if (state.backtracking > 0) {
        memoize(input, 66, rhs_StartIndex);
      }
    }
    return retval;
  }