def METHOD_NAME(self, widget, node):
    # open the file or folder in the platform's default app
    self.label.text = f"You started {node.path}"
    if platform.system() == "Darwin":
        subprocess.call(("open", node.path))
    elif platform.system() == "Windows":
        os.startfile(node.path)
    else:
        subprocess.call(("xdg-open", node.path))