when<T>  method 
      
T
when<T>({  
    
    
- required T sameTab(- WebAuthenticationSameTab sameTab
 
- required T popup(- WebAuthenticationPopup popup
 
Implementation
T when<T>({
  required T Function(WebAuthenticationSameTab sameTab) sameTab,
  required T Function(WebAuthenticationPopup popup) popup,
}) {
  if (this is WebAuthenticationSameTab) {
    return sameTab(this as WebAuthenticationSameTab);
  } else if (this is WebAuthenticationPopup) {
    return popup(this as WebAuthenticationPopup);
  } else {
    throw StateError(
      'Instance of WebAuthenticationMode is not a known subtype',
    );
  }
}