def checkable(self, value):
        """
        Setter for **self.__checkable** attribute.

        :param value: Attribute value.
        :type value: bool
        """

        if value is not None:
            assert type(value) is bool, "'{0}' attribute: '{1}' type is not 'bool'!".format("checkable", value)
        self.__checkable = value
Setter for **self.__checkable** attribute.

        :param value: Attribute value.
        :type value: bool