title: IDictionary interface without Remove()
body: <p>Is there an IDictionary interface which does not support removal of Key-Value pairs?</p>
  
  <p>Unfortunately, <code>IReadOnlyDictionary</code> does not help as it does not allow to modify the Key-Value pairs.</p>
  
  <p>If not, what's a good way to implement one myself? Is this even a good idea?</p>