or'>, </span><span class='decorator'>action</span><span class='decorator'>: (</span><span class='decorator'>inout</span><span class='decorator empty-token'> </span><span class='decorator'>Element</span><span class='decorator'>) -&gt; </span><span class='decorator'>Result</span><span class='decorator'>) -&gt; </span><span class='decorator'>Result</span></code>
                </a>
              
              
              <div class="abstract">
                <div class="content">Atomically mutate this su