title: Error: Extension method must be defined in a non-generic static class
body: <p>I get the following compilation error at the class name.</p>
  
  <p><code>Extension method must be defined in a non-generic static class</code></p>
  
  <p>I am not using normal class. What could be the reason for this. I don't know and don't want to use extension methods. </p>