def __init__(self, screen, x, y, life_time, on_destroy=None):
        """
        :param screen: The Screen being used for this particle system.
        :param x: The column (x coordinate) for the origin of the rocket.
        :param y: The line (y coordinate) for the origin of the rocket.
        :param life_time: The life time of the rocket.
        :param on_destroy: The function to call when the rocket explodes.
        """
        super(Rocket, self).__init__(
            screen, x, screen.height - 1, 1, self._new_particle, 1, life_time)
        self._end_y = y
        self._acceleration = (self._y - self._end_y) // life_time
        self._on_destroy = on_destroy
dataset/ETHPy150Open peterbrittain/asciimatics/asciimatics/particles.py/Rocket.__init__/swapped operands of `-`