type <code class="computeroutput"><span class="identifier">Num</span></code>
            to instantiate a <code class="computeroutput"><span class="identifier">real_generator</span><span class="special">&lt;</span><span class="identifier">Num</span><span class="special">,</span> <span class="identifier">Policies</span><span class="special">&gt;</span></code>.
          </p>
<p>
            In order to be usable as the first template parameter for <code class="computeroutput"><span class="identifier">real_ge