title: Search array keys with wildcard
body: <p>Say I have the following array:</p>
  
  <pre><code>$arr = array(
     "number2"=&gt;"valid",
     "number13"=&gt;"valid"
  );
  </code></pre>
  
  <p>and I need to find if there is a key that exists with <code>number*</code>.</p>
  
  <p>For <code>$arr</code>, this would be true. For the following array:</p>
  
  <pre><code>$arr2 = array(
     "key"=&gt;"foo",
     "key2"=&gt;"foo2"
  );
  </code></pre>
  
  <p>this would return false.</p>