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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _load_fields(new_class, attrs):
 """Load field items into Class. This method sets up the primary attribute of an association. If Child class has defined an attribute so `parent = field.Reference(Parent)`, then `parent` is set up in this method, while `parent_id` is set up in `_set_up_reference_fields()`. """

        for attr_name, attr_obj in attrs.items():
            if isinstance(attr_obj, (Field, Reference)):
                setattr(new_class, attr_name, attr_obj)
                new_class.meta_.declared_fields[attr_name] = attr_obj