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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 disable_restricted(self, ):
 """Disable the restricted buttons :returns: None :rtype: None :raises: None """

        todisable = [(self.reftrack.duplicate, self.duplicate_tb),
                     (self.reftrack.delete, self.delete_tb),
                     (self.reftrack.reference, self.reference_tb),
                     (self.reftrack.replace, self.replace_tb),]
        for action, btn in todisable:
            res = self.reftrack.is_restricted(action)
            btn.setDisabled(res)