def roles(self, value):
        """
        Setter for **self.__roles** attribute.

        :param value: Attribute value.
        :type value: dict
        """

        if value is not None:
            assert type(value) is dict, "'{0}' attribute: '{1}' type is not 'dict'!".format("roles", value)
            for key in value:
                assert type(key) is Qt.ItemDataRole, "'{0}' attribute: '{1}' type is not 'Qt.ItemDataRole'!".format(
                    "roles", key)
        self.__roles = value