def unset_values(self):
        """
        Removes any user values from all symbols, as if Kconfig.load_config()
        or Symbol.set_value() had never been called.
        """
        self._warn_assign_no_prompt = False
        try:
            # set_value() already rejects undefined symbols, and they don't
            # need to be invalidated (because their value never changes), so we
            # can just iterate over defined symbols
            for sym in self.unique_defined_syms:
                sym.unset_value()

            for choice in self.unique_choices:
                choice.unset_value()
        finally:
            self._warn_assign_no_prompt = True

        Removes any user values from all symbols, as if Kconfig.load_config()
        or Symbol.set_value() had never been called.
        
buildroot-external/scripts/kconfiglib.py