The `lambda_body` grammar rule has a `"}"`, which is throwing off the `exyacc.rb` regular expressions. This changes the regular expression to account for `"}"` as well, which makes the output of `ruby sample/exyacc.rb < parse.y` change by the following diff:

```diff
632,634d631
< 		    ", &@3);
< 			$$ = $2;
< 		    }
```

Which makes it closer to a valid EBNF.