ks correctly even if <code class="code">src</code> and <code class="code">dst</code> are the
    same byte sequence, and the source and destination intervals
    overlap.</p>

<p>Raise <code class="code"><span class="constructor">Invalid_argument</span></code> if <code class="code">srcoff</code> and <code class="code">len</code> do not
    designate a valid range of <code class="code">src</code>, or if <code class="code">dstoff</code> and <code class="code">len</code>
    do not designate a valid range of <