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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 pre_render(self):
 """Last things to do before rendering"""

        self.add_styles()
        self.add_scripts()
        self.root.set(
            'viewBox', '0 0 %d %d' % (self.graph.width, self.graph.height)
        )
        if self.graph.explicit_size:
            self.root.set('width', str(self.graph.width))
            self.root.set('height', str(self.graph.height))