/div>
</div>
<p class="continue">We can&rsquo;t just use <code>applyCheck</code> as the handler for <code>Identifier</code>
because <code>walk.simple</code> wouldn&rsquo;t know how to call it.
This is a (very simple) example of the <span class="ix-entry" ix-key="Adapter pattern;design pattern!Adapter" markdown="1"><a class="gl-ref" href="../glossary/#adapter_pattern" markdown="1">Adapter</a></span> design pattern:
we write a function or class to connect the code we want to call
to the already-written code t