'Yield objects that pass the filter.
Can be overridden in a subclass, if you need to base filtering
decisions on all objects.  Otherwise, one can just override
_filter_one() to filter a single object.'

def filter_all(self, filter_obj_list, filter_properties):

    for obj in filter_obj_list:
        if self._filter_one(obj, filter_properties):
            (yield obj)
