r</code> is
   full, <code class="code"><span class="keyword">false</span></code> if it is empty.  Note that even if <code class="code"><span class="constructor">Weak</span>.check ar n</code>
   returns <code class="code"><span class="keyword">true</span></code>, a subsequent <a href="Weak.html#VALget"><code class="code"><span class="constructor">Weak</span>.get</code></a><code class="code"> ar n</code> can return <code class="code"><span class="constructor">None</span></code>.<br>
</div>

<pre><span id="VA