def addItem(self, itemId=None):
        if itemId is None:
            idd = self._container.addItem()
            if not self._ordered and (idd is not None):
                self.addToOrderWrapper(idd)
            return idd
        else:
            item = self._container.addItem(itemId)
            if not self._ordered and (item is not None):
                self.addToOrderWrapper(itemId)
            return item
Creates a new Item into the Container, assigns it an automatic ID,
dataset/ETHPy150Open rwl/muntjac/muntjac/data/util/container_ordered_wrapper.py/ContainerOrderedWrapper.addItem