aluate it in its environment. We use <code>actual-value</code> instead of <code>eval</code> so that it recursively forces if the result is another thunk:</li>
</ul>
<pre><code class="codeblock">(<span class="kw">define</span> (force-it obj)
  (<span class="kw">if</span> (thunk? obj)
      (actual-value (thunk-exp obj) (thunk-env obj))
      obj))</code></pre>
<ul>
<li>We can represent thunks simply by a list containing the expression and environment:</li>
</ul>
<pre><code class="codeblock">(<span class="kw"