@classmethod
def _updateClassDictWithBaseItems(cls, bases, classdict):
    """Copy each of the items from the base class that hasn't been
        explicitly defined in the new class."""
    if bases:
        base_class = bases[0]
        if hasattr(base_class, 'items'):
            for item in base_class.items:
                if item.name not in classdict:
                    new_item = cls.item_type.construct(item)
                    classdict[item.name] = new_item
