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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 get_scales(self, aesthetic):
 """ Return the scale for the aesthetic or None if there isn't one. These are the scales specified by the user e.g `ggplot() + scale_x_continuous()` or those added by default during the plot building process """

        bool_lst = self.find(aesthetic)
        try:
            idx = bool_lst.index(True)
            return self[idx]
        except ValueError:
            return None