/code>.<br>
</div>
<pre><span id="VALusage_string"><span class="keyword">val</span> usage_string</span> : <code class="type">(<a href="Arg.html#TYPEkey">key</a> * <a href="Arg.html#TYPEspec">spec</a> * <a href="Arg.html#TYPEdoc">doc</a>) list -&gt; <a href="Arg.html#TYPEusage_msg">usage_msg</a> -&gt; string</code></pre><div class="info">
Returns the message that would have been printed by <a href="Arg.html#VALusage"><code class="code"><span class="constructor">Arg</span>.usage</code></a>,
    if provided wi