title: Check if key exist in one of the objects
body: <p>I would like to check if a key exist in one of the objects : </p>
  
  <pre><code>array (size=2)
    0 =&gt; 
      object(stdClass)[1631]
        public 'label' =&gt; string 'Monsieur' (length=8)
        public 'value' =&gt; string '1' (length=1)
        public 'selected' =&gt; boolean true
    1 =&gt; 
      object(stdClass)[1633]
        public 'label' =&gt; string 'Madame' (length=6)
        public 'value' =&gt; string '2' (length=1)
  </code></pre>
  
  <p>In the example I have one array who contain two objects, the first one contain 'selected' key. I would like to return true if one of them contain 'selected' key. If the objects not contain 'selected' key I would like to return false. </p>
  
  <p>I can have more than two objects. This is only for the example. Is there a function for this?</p>