def METHOD_NAME(self) -> None:
    if not self.exec_():
        return
    if self.is_preview:
        self.main_window.show_transaction(self.tx)
        return
    def sign_done(success):
        if success:
            self.main_window.broadcast_or_show(self.tx)
    self.main_window.sign_tx(
        self.tx,
        callback=sign_done,
        external_keypairs={})