title: Add 'set' to properties of interface in C#
body: <p>I am looking to 'extending' an interface by providing set accessors to properties in that interface.  The interface looks something like this:</p>
  
  <pre><code>interface IUser
  {
      string UserName
      {
          get;
      }
  }
  </code></pre>
  
  <p>I want something like this:</p>
  
  <pre><code>interface IMutableUser : IUser
  {
      string UserName
      {
          get;
          set;
      }
  }
  </code></pre>
  
  <p>I need the inheritence.  I cannot copy the body of <code>IUser</code> into <code>IMutableUser</code> and add the set accessors.</p>
  
  <p>Is this possible in C#?  If so, how can it be accomplished?</p>