t;</span> <span class="identifier">bg</span><span class="special">::</span><span class="identifier">wkt</span><span class="special">&lt;</span><span class="identifier">box</span><span class="special">&gt;(</span><span class="identifier">v</span><span class="special">.</span><span class="identifier">first</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="string">" - "</span> <span class="special">&lt;&lt;</span> <span class="identifier">v</span><span class="special">.</s