def __init__(self, *args, **kwargs):
        super(AbstractAddressForm, self).__init__(*args, **kwargs)
        field_names = (set(self.fields) &
                       set(settings.OSCAR_REQUIRED_ADDRESS_FIELDS))
        for field_name in field_names:
            self.fields[field_name].required = True
Collapses the items recursively.
dataset/ETHPy150Open django-oscar/django-oscar/src/oscar/apps/address/forms.py/AbstractAddressForm.__init__--crossover with--dataset/ETHPy150Open rwl/muntjac/muntjac/ui/tree.py/Tree.collapseItemsRecursively