Setter for **self.__anchor** attribute.

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

def anchor(self, value):
        """
        Setter for **self.__anchor** 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("anchor", value)
            assert value in range(
                0, 9), "'{0}' attribute: '{1}' need to be in '0' to '8' range!".format("anchor", value)
        self.__anchor = value