title: Can I use inheritance with an extension method?
body: <p>I have the following:</p>
  
  <pre><code>public static class CityStatusExt
  {
      public static string D2(this CityStatus key)
      {
          return ((int) key).ToString("D2");
      }
  
  
  public static class CityTypeExt
  {
      public static string D2(this CityType key)
      {
          return ((int) key).ToString("D2");
      }
  </code></pre>
  
  <p>Plus other classes with similar extensions that return the key formatted as a "D2"</p>
  
  <p>Is there a way I could inherit from a base class and have the base class provide the functionality so 
  don't I don't have to repeat the same extension method code?</p>
  
  <p><strong>Update.</strong> I am sorry I did not mention this but my classes like CityType are Enums. </p>