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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 diff(self, plot):
 """ Returns the latest plot data to update an existing plot. """

        if self.fig == 'auto':
            figure_format = self.params('fig').objects[0]
        else:
            figure_format = self.fig
        return self.html(plot, figure_format)