@abc.abstractmethod<EOL><INDENT>def is_published(self):<DEDENT>
return<EOL>
Tests if this asset has been published.

        Not all assets viewable in this repository may have been
        published. The source of a published asset indicates the
        publisher.

        :return: true if this asset has been published, ``false`` if unpublished or its published status is not known
        :rtype: ``boolean``


        *compliance: mandatory -- This method must be implemented.*