Setter for **self.__variables** attribute.

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

def variables(self, value):
        """
        Setter for **self.__variables** 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("variables", value)
            for key, element in value.iteritems():
                assert type(key) is unicode, "'{0}' attribute: '{1}' type is not 'unicode'!".format(
                    "variables", key)
                assert type(element) is unicode, "'{0}' attribute: '{1}' type is not 'unicode'!".format(
                    "variables", element)
        self.__variables = value