    def __init__(self, screen, life_time):
        """
        :param screen: The Screen being used for this particle system.
        :param life_time: The life time of this particle system.
        """
        super().__init__(
            screen, 0, 0, 20, self._next_particle, life_time, life_time)
        self._particles = None
        self._full_count = 0
:param screen: The Screen being used for this particle system.
:param life_time: The life time of this particle system.
asciimatics/particles.py