def is_opus_maximum(self):
        """Check whether the work is the author's opus maximum.

        Two cases:
        1. the work is flagged as opus max
        2. there is only one work by this author

        :return: boolean
        """
        opmax = self._get_opus_maximum()
        types = self.ecrm_P2_has_type

        if opmax in types:
            return True
        else:
            if len(self.author.get_works()) == 1:
                return True
            else:
                return False
Check whether the work is the author's opus maximum.

        Two cases:
        1. the work is flagged as opus max
        2. there is only one work by this author

        :return: boolean