     // string encoding
     
     /// reinterpret file with the desired encoding and show error dialog if failed
-    @discardableResult
     func reinterpretAndShowError(encoding: String.Encoding) {
         
         do {

            alert.alertStyle = .critical
        }
        
        self.isExternalUpdateAlertShown = true
        self.windowForSheet?.orderFront(self)
        
        // display alert
        alert.beginSheetModal(for: self.windowForSheet!) { [weak self] (returnCode: NSModalResponse) in
            guard let strongSelf = self else { return }
            
            if returnCode == NSAlertSecondButtonReturn, let fileType = strongSelf.fileType {  // == Revert
                do {
                    try strongSelf.revert(toContentsOf: fileURL, ofType: fileType)
                } catch {
                    strongSelf.presentErrorAsSheet(error)
                }
            }
            
            strongSelf.isExternalUpdateAlertShown = false
            strongSelf.needsShowUpdateAlertWithBecomeKey = false
        }
    }
    

            switch option {
            case .ignore:
                break
            case .notify:
                self?.showUpdatedByExternalProcessAlert()
            case .revert:
                self?.revertWithoutAsking()
            }
        }
    }
