def addStringFromLineEdit(self):
        text = self.inputLine.text()
        if not text:
            return
        try:
            self.model.add(text)
        except AlreadyThereException:
            self.app.show_message("Expression already in the list.")
            return
        except Exception as e:
            self.app.show_message(f"Expression is invalid: {e}")
            return
        self.inputLine.clear()