lass="keyword">noexcept</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_nothrow_move_constructible</span><span class="special">&lt;</span> <span class="identifier">base_type</span> <span class="special">&gt;</span><span class="special">::</span><span class="identifier">value</span> <span class="special">&amp;&amp;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">is_nothrow_mo