Setter for **self.__paths** attribute.

        :param value: Attribute value.
        :type value: tuple or list

def paths(self, value):
        """
        Setter for **self.__paths** attribute.

        :param value: Attribute value.
        :type value: tuple or list
        """

        if value is not None:
            assert type(value) in (tuple, list), "'{0}' attribute: '{1}' type is not 'tuple' or 'list'!".format(
                "paths", value)
            for element in value:
                assert type(element) is unicode, "'{0}' attribute: '{1}' type is not 'unicode'!".format(
                    "paths", element)
                assert os.path.exists(element), "'{0}' attribute: '{1}' directory doesn't exists!".format("paths",
                                                                                                          element)
        self.__paths = value