ass="special">::</span><span class="identifier">int128_type</span></code> and <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">uint128_type</span></code>
          where available - currently only <code class="computeroutput"><span class="identifier">__int128</span></code>
          and <code class="computeroutput"><span class="keyword">unsigned</span> <span class="identifier">__int128</span></code>
          on some versions of gcc.
 