@abc.abstractmethod<EOL><INDENT>def get_comments_by_genus_type(self, comment_genus_type):<DEDENT>
return<EOL>
Gets a ``CommentList`` corresponding to the given comment genus ``Type`` which does not include comments of genus types derived from the specified ``Type``.

        :param comment_genus_type: a comment genus type
        :type comment_genus_type: ``osid.type.Type``
        :return: the returned ``Comment`` list
        :rtype: ``osid.commenting.CommentList``
        :raise: ``NullArgument`` -- ``comment_genus_type`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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