hen an ego attribute is used the <code>.f</code> is called like this:
<code>.f(alt.attr, ego.attr, ...)</code>. <code>.f</code> must return a single numeric value.</p>
    </div>
    <div class="section level2">
    <h2 id="author">Author<a class="anchor" aria-label="anchor" href="#author"></a></h2>
    <p>Michał Bojanowski, <a href="mailto:michal2992@gmail.com">michal2992@gmail.com</a></p>
<p>Till Krenz, <a href="mailto:egor@tillt.net">egor@tillt.net</a></p>
    </div>

    <div class="section level2">
  