title: C# passing List parameter
body: <p>If I am writing a method that accepts two list parameters like so:</p>
  
  <pre><code>public void ModifyYourListsHere(List&lt;MyClass1&gt; list1, List&lt;MyClass2&gt; list2)
  {
      ...add and remove from the lists
  }
  </code></pre>
  
  <p>Should I pass these as <code>ref</code> or <code>out</code> if I want the caller to understand that the lists will be modified? Or do I just need to document the method? Or should the user expect that they might be modified?</p>