title: shortcut to validate if an array exists and contains no values
body: <p>What is a shortcut to validate if an array exists and contains no values?</p>
  
  <p>for some reason, this looks weird</p>
  
  <pre><code>$warning = array();
  
  if (isset($warning) &amp;&amp; empty($warning)) {
     //go on...
  } else {
    //either the array doesn't exist or it exist but contains values...
  }
  </code></pre>
  
  <p>the array needs to exist and must contain no values</p>