r">base2_type</span><span class="special">;</span>

<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">system</span><span class="special">(</span> <span class="keyword">double</span> <span class="identifier">x</span> <span class="special">);</span>
    <span class="comment">//...</span>
<span class="special">};</span>

<span class="identifier">system</span><span class="special">::</span><span class="identifier">system</span><span class="special">(</span> <span cla