how to get the keys of sub array from this array tree
<p>How to get the keys 151,152 from this nested array and store them as a separate array     </p>

<pre><code>Array  
   (  
    [151] =&gt; Array  
        ( 
            [152] =&gt; Array  
                (  
                )  

        )  

   )  
</code></pre>
