Use :class:`PyLauncher` to submits one task.
        kwargs contains the options passed to the launcher.

        Return:
            number of tasks submitted.

def single_shot(self, check_status=True, **kwargs):
        """
        Use :class:`PyLauncher` to submits one task.
        kwargs contains the options passed to the launcher.

        Return:
            number of tasks submitted.
        """
        self.check_pid_file()
        self.set_spectator_mode(False)
        if check_status: self.check_status()
        from .launcher import PyLauncher
        return PyLauncher(self, **kwargs).single_shot()