pan class="special">=</span> <span class="identifier">m</span><span class="special">.</span><span class="identifier">value_</span><span class="special">;</span>   <span class="identifier">m</span><span class="special">.</span><span class="identifier">value_</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>  <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span>  <span class="special">}<