title: Unable to modify IList object's members
body: <p>I have created an IList variable as below:</p>
  
  <pre><code>IList&lt;vertex&gt; matrix = new List&lt;vertex&gt; ();
  </code></pre>
  
  <p>Here, vertex is a structure I defined with one of the members being visited (boolean).</p>
  
  <p>But, when I try to modify this member by traversing through the list as below:</p>
  
  <pre><code>matrix[j].visited = false;
  </code></pre>
  
  <p>It gives an error saying "Cannot modify return value because it is not a variable". Any idea why?</p>