class="special">,</span> <span class="identifier">M</span><span class="special">&gt;</span></code>
            returns the actual type returned by <code class="computeroutput"><a class="link" href="../intrinsic/functions/at.html" title="at"><code class="computeroutput"><span class="identifier">at</span></code></a><span class="special">&lt;</span><span class="identifier">M</span><span class="special">&gt;(</span><span class="identifier">s</span><span class="special">)</span></code>.
            In most cases