ode class="code">n</code> bytes or fewer in <code class="code">s</code>,
   starting at index 0, and return the number of bytes
   provided. A return value of 0 means end of input.</p>
</div>
</div>

<pre id="VALset_position">val set_position : lexbuf -&gt; position -&gt; unit</pre><div class="info ">
<div class="info-desc">
<p>Set the initial tracked input position for <code class="code">lexbuf</code> to a custom value.
   Ignores <code class="code">pos_fname</code>. See <a href="Lexing.html#VALset_filenam