s="Identifier">Once</span></a> <span class="Other">=</span> <span class="Keyword">object</span></pre></dt>
  <dd>
    
    Once is a type that allows you to execute a block of code exactly once. The first call to <tt class="docutils literal"><span class="pre"><span class="Identifier">once</span></span></tt> will execute the block of code and all other calls will be ignored. All concurrent calls to <tt class="docutils literal"><span class="pre"><span class="Identifier">once</span></span></tt> are guaranteed 