 class="constructor">Arg</span>.parse_argv</code> when the user asks for help.<br>
</div>
<pre><span id="EXCEPTIONBad"><span class="keyword">exception</span> Bad</span> <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
Functions in <code class="code">spec</code> or <code class="code">anon_fun</code> can raise <code class="code"><span class="constructor">Arg</span>.<span class="constructor">Bad</span></code> with an error
    message to reject invalid arguments.
    <c