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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 raise_on_wrong_settings(self):
 """ Validates the configuration settings and raises RuntimeError on error """

        self.__ensure_dir_exists(self.working_directory, 'working directory')
        for idir in self.include_paths:
            self.__ensure_dir_exists(idir, 'include directory')
        if self.__xml_generator not in ["castxml", "gccxml"]:
            msg = ('xml_generator("%s") should either be ' +
                   '"castxml" or "gccxml".') % self.xml_generator
            raise RuntimeError(msg)