How do I extend a class with c# extension methods?
<p>Can extension methods be applied to the class?</p>

<p>For example, extend DateTime to include a Tomorrow() method that could be invoked like:</p>

<pre><code>DateTime.Tomorrow();
</code></pre>

<p>I know I can use </p>

<pre><code>static DateTime Tomorrow(this Datetime value) { //... }
</code></pre>

<p>Or</p>

<pre><code>public static MyClass {
  public static Tomorrow() { //... }
}
</code></pre>

<p>for a similar result, but how can I extend DateTime so that I could invoke DateTime.Tomorrow?</p>
