How to use the rwslib.builders.clinicaldata.Annotation function in rwslib

def __lshift__(self, other):
        if not isinstance(other, (Annotation,)):
            raise ValueError("Annotations cannot accept a child element of type %s" % other.__class__.__name__)

        self.set_list_attribute(other, Annotation, 'annotations')
        return other

def __init__(self, annotation_id=None, seqnum=1,
                 flags=None, comment=None,
                 transaction_type=None):
        """
        :param id: ID for this Annotation (required if contained within an Annotations element)
        :type id: str or None
        :param int seqnum: :attr:`SeqNum` for Annotation
        :param flags: one or more :class:`Flag` for the Annotation
        :type flags: Flag or list(Flag)
        :param comment: one or more :class:`Comment` for the Annotation
        :type comment: Comment
        :param transaction_type: :attr:`TransactionType` for Annotation (one of **Insert**, **Update**, *Remove*, **Upsert**, **Context**)
        """
        super(Annotation, self).__init__(transaction_type=transaction_type)
        # initialise the flags collection
        self.flags = []
        if flags:
            if isinstance(flags, (list, tuple)):
                for flag in flags:
                    self << flag
            elif isinstance(flags, Flag):
                self << flags
            else:
                raise AttributeError("Flags attribute should be an iterable or Flag")
        self._id = None
        if annotation_id is not None:
            self.annotation_id = annotation_id
        self._seqnum = None
        if seqnum is not None:
            # validate the input

def __lshift__(self, other):
        if not isinstance(other, (Annotation,)):
            raise ValueError("Annotations cannot accept a child element of type %s" % other.__class__.__name__)

        self.set_list_attribute(other, Annotation, 'annotations')
        return other

whole_item_group=False, annotations=None):
        """
        :param str transaction_type: TransactionType for the ItemGroupData
        :param int item_group_repeat_key: RepeatKey for the ItemGroupData
        :param bool whole_item_group: Is this the entire ItemGroupData, or just parts? - *Rave specific attribute*
        :param annotations: Annotation for the ItemGroup - *Not supported by Rave*
        :type annotations: list(Annotation) or Annotation
        """
        super(self.__class__, self).__init__(transaction_type)
        self.item_group_repeat_key = item_group_repeat_key
        self.whole_item_group = whole_item_group
        self.items = OrderedDict()
        self.annotations = []
        if annotations:
            # Add the annotations
            if isinstance(annotations, Annotation):
                self << annotations
            elif isinstance(annotations, list):
                for annotation in annotations:
                    self << annotation
        #: :class:`Signature` for ItemGroupData
        self.signature = None
        self.itemgroupoid = itemgroupoid

def mixin(self):
        """
        Add the annotations to the ODM Element (if defined)
        :return: 
        """
        if self.milestones:
            from rwslib.builders.clinicaldata import Annotation, Flag, FlagValue
            annotation = Annotation()
            for codelist, milestones in self.milestones.items():
                for milestone in milestones:
                    annotation << Flag() << FlagValue(milestone, codelist_oid=codelist)
            self.annotations.append(annotation)