def tag(self, *tags):
        """
        Tags the job with one or more unique indentifiers.

        Tags must be hashable. Duplicate tags are discarded.

        :param tags: A unique list of ``Hashable`` tags.
        :return: The invoked job instance
        """
        if not all(isinstance(tag, collections.Hashable) for tag in tags):
            raise TypeError('Tags must be hashable')
        self.tags.update(tags)
        return self