p>argument:
<ul>
<li><p><code>t</code>: integer, time step <code>t</code>.</p></li>
</ul>
returns a named <code>list</code>
containing the current <code>d x k</code> dimensional matrix <code>context$X</code>,
the number of arms <code>context$k</code> and the number of features <code>context$d</code>.</p></dd>
    <dt><code>get_reward(t, context, action)</code></dt><dd><p>arguments:
<ul>
<li><p><code>t</code>: integer, time step <code>t</code>.</p></li>
<li><p><code>context</code>: list, containing the curre