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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 restore_default(self, index):
 """Set the value of the given index row to its default :param index: :type index: :returns: :rtype: :raises: """

        spec = self.get_configspec_str(index)
        if spec is None or isinstance(spec, Section):
            return
        try:
            default = self._vld.get_default_value(spec)
            defaultstr = self._val_to_str(default)
            self.setData(index, defaultstr)
        except KeyError:
            raise ConfigError("Missing Default Value in spec: \"%s\"" % spec)