def default_line_number_width(self, value):
        """
        Setter for **self.__default_line_number_width** attribute.

        :param value: Attribute value.
        :type value: int
        """

        if value is not None:
            assert type(value) is int, "'{0}' attribute: '{1}' type is not 'int'!".format(
                "default_line_number_width", value)
            assert value > 0, "'{0}' attribute: '{1}' need to be exactly positive!".format(
                "default_line_number_width", value)
        self.__default_line_number_width = value
Setter for **self.__default_line_number_width** attribute.

        :param value: Attribute value.
        :type value: int