60;&#160; <span class="Statement">throw</span>&#160;<span class="Keyword">new</span> ArgumentNullException(<span class="String">&quot;predicate&quot;</span>);     <br />&#160;&#160;&#160; }     <br />&#160;&#160;&#160; <span class="Statement">return</span> WhereImpl(source, predicate);     <br />}     <br />    <br /><span class="Modifier">private</span>&#160;<span class="Modifier">static</span> IEnumerable&lt;TSource&gt; WhereImpl&lt;TSource&gt;(     <br />&#160;&#160;&#160; <span class="Keyword">this</spa