def __iadd__(self, item):
        """Add the item to the corresponding type list.  Allows "+=" syntax."""
        if isinstance(item, list):
            for i in item:
                self.__add(i)
        else:
            self.__add(item)
        return self
Add the item to the corresponding type list.  Allows "+=" syntax.
hpccm/building_blocks/scif.py