    def __init__(self, screen, life_time, on_each):
        """
        :param screen: The Screen being used for this particle system.
        :param life_time: The life time of this particle system.
        :param on_each: Function to call on each iteration of the particle.
        """
        super().__init__(
            screen, 0, 0, 4, self._next_particle, life_time, life_time)
        self._particles = None
        self._on_each = on_each
:param screen: The Screen being used for this particle system.
:param life_time: The life time of this particle system.
:param on_each: Function to call on each iteration of the particle.
asciimatics/particles.py