title: could someone explain that C++ code for me?
body: <p>In the following code what is the meaning of colon? and where callback function came from?</p>
  
  <pre class="lang-cpp prettyprint-override"><code>using void_callback_f = void (*)();
  std::vector&lt;void_callback_f&gt; _reload_callbacks;
  
  void Reload() {
      for (const auto&amp; callback : _reload_callbacks) {
          callback();
      }
  }
  </code></pre>