r">boost</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">double</span><span class="special">,</span> <span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">point_t</span><span class="special">;</span>

  <span class="keyword">const</span> <span class="identifier">std</span><span class="special">::</span><span class="identifi