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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def save_gif(self, filename):
 """Saves the animation to a gif A convience function. Provided to let the user avoid dealing with writers. Parameters filename : str the name of the file to be created without the file extension """

        self.timeline.index -= 1  # required for proper starting point for save
        self.animation.save(filename+'.gif', writer=PillowWriter(fps=self.timeline.fps))