f="Buffer.html#TYPEt">t</a> -&gt; int -&gt; int -&gt; string</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code"><span class="constructor">Buffer</span>.sub&nbsp;b&nbsp;off&nbsp;len</code> returns a copy of <code class="code">len</code> bytes from the
    current contents of the buffer <code class="code">b</code>, starting at offset <code class="code">off</code>.</p>

<p>Raise <code class="code"><span class="constructor">Invalid_argument</span></code> if <code class="code">srcoff</