/a> instance <code class="computeroutput"><span class="identifier">x</span></code> can be invoked by using the function-call
          operator of the corresponding attribute:
        </p>
<pre class="programlisting"><span class="identifier">x</span><span class="special">.</span><span class="identifier">attr</span><span class="special">(</span><span class="string">"tea"</span><span class="special">)(</span><span class="number">4</span><span class="special">,</span> <span class="number">2</span><span class="