title: convert List<List<object>> to IList<IList<object>>
body: <p>I have written a method which is 
      <code>public List&lt;List&lt;object&gt;&gt; Fetch(string data)</code>, 
  inside I create 
      <code>List&lt;List&lt;object&gt;&gt; p = new List&lt;List&lt;object&gt;&gt;();</code></p>
  
  <p>my boss now wants to return a <code>IList&lt;IList&lt;object&gt;&gt;</code> instead of <code>List&lt;List&lt;object&gt;&gt;</code> ie<br>
      <code>public IList&lt;IList&lt;object&gt;&gt; Fetch(string data)</code>, </p>
  
  <p>so when I try do
      <code>return (IList&lt;IList&lt;object&gt;&gt;) p; //throws an exception</code></p>
  
  <p>How do I convert 
    <code>List&lt;List&lt;object&gt;&gt;</code> to <code>IList&lt;IList&lt;object&gt;&gt;</code>  and back to <code>List&lt;List&lt;object&gt;&gt;</code></p>