    def __init__(self, screen, pattern):
        """
        :param screen: The Screen being used for the Scene.
        :param pattern: The pattern to loop through
        """
        self._screen = screen
        self._star_chars = pattern
        self._cycle = None
        self._old_char = None
        self._respawn()
:param screen: The Screen being used for the Scene.
:param pattern: The pattern to loop through
asciimatics/effects.py