Add the structured data from items to the CryoTank.

        Args:
            items (list):  A list of objects to store in the CryoTank.
            seqn (iden, offs): An iden / offset pair to record.

        Returns:
            int: The ending offset of the items or seqn.

async def puts(self, items, seqn=None):
        '''
        Add the structured data from items to the CryoTank.

        Args:
            items (list):  A list of objects to store in the CryoTank.
            seqn (iden, offs): An iden / offset pair to record.

        Returns:
            int: The ending offset of the items or seqn.
        '''
        size = 0

        for chunk in s_common.chunks(items, 1000):
            metrics = self._items.save(chunk)
            self._metrics.add(metrics)
            await self.fire('cryotank:puts', numrecords=len(chunk))
            size += len(chunk)
            await asyncio.sleep(0)

        if seqn is not None:
            iden, offs = seqn
            self.setOffset(iden, offs + size)

        return size