com/inkytonik/kiama/issues/83/cached-attributes-arent-thread-safe">Issue 83</a>
            Cached attributes are now synchronized so that cache management is now thread safe. As a side effect of this
            change, it is no longer possible to define attribute types that are not inheriting from <code>AnyRef</code>.
            Thanks to Fred Teunissen for reporting and helping with testing.</p>
    </li>
    <li>
        <p><code>PrettyPrinter</code>: The <code>string</code> method now uses an iterator