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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(self, annot=None, output_path=None):
 """Saves the collage to disk as an image. Parameters annot : str text to annotate the figure with a super title output_path : str path to save the figure to. Note: any spaces in the filename will be replace with ``_`` """


        if annot is not None:
            self.fig.suptitle(annot, backgroundcolor='black', color='g')

        if output_path is not None:
            output_path = output_path.replace(' ', '_')
            # TODO improve bbox calculations to include ONLY the axes from collage
            # and nothing else
            self.fig.savefig(output_path + '.png', bbox_inches='tight', dpi=200,
                             bbox_extra_artists=self.flat_grid)