its immediate parameter as its attribute.
          </li>
<li class="listitem">
            Added boolean parsers and generators (<code class="computeroutput"><span class="identifier">bool_</span></code>,
            <code class="computeroutput"><span class="identifier">true_</span></code>, <code class="computeroutput"><span class="identifier">false_</span></code>).
          </li>
<li class="listitem">
            Added <code class="computeroutput"><span class="identifier">attr_cast</span><span class="spec