title: Is it OK? clearOverlays() in GMap API V2 to Google Maps API V3?
body: <p>I use Google Maps API V3. </p>
  
  <p>I migrate My site GMap API V2 -> V3.
   but coped because I used the clearOverlays() method to delete an existing object at once in the V2 , and it deleted an object in what had been abolished in V3 individually.</p>
  
  <p><strong>V2</strong></p>
  
  <pre class="lang-js prettyprint-override"><code>map.clearOverlays();
  </code></pre>
  
  <p><strong>V3</strong></p>
  
  <pre class="lang-js prettyprint-override"><code>map.set_visible(false);
  popup.close();
  </code></pre>
  
  <p>is it OK? 
  or other solutions?</p>