public function Clear($ConversationID = FALSE, $TransientKey = '') {
      $Session = Gdn::Session();
      
      // Yes/No response
      $this->_DeliveryType = DELIVERY_TYPE_BOOL;
      
      $ValidID = (is_numeric($ConversationID) && $ConversationID > 0);
      $ValidSession = ($Session->UserID > 0 && $Session->ValidateTransientKey($TransientKey));
      
      if ($ValidID && $ValidSession) {
         // Clear it
         $this->ConversationModel->Clear($ConversationID, $Session->UserID);
         $this->InformMessage(T('The conversation has been cleared.'));
         $this->RedirectUrl = Url('/messages/all');
      }
      
      $this->Render();
   }