def get_natural_key_fields(cls):
        """
        Determine actual natural key field list, incorporating the natural keys
        of related objects as needed.
        """
        natural_key = []
        for name, rel_to in cls.get_natural_key_info():
            if not rel_to:
                natural_key.append(name)
            else:
                nested_key = rel_to.get_natural_key_fields()
                natural_key.extend([
                    name + '__' + nname
                    for nname in nested_key
                ])
        return natural_key
def get_natural_key_fields ( cls ) : natural_key = [ ] for name , rel_to in cls . get_natural_key_info ( ) : if not rel_to : natural_key . append ( name ) else : nested_key = rel_to . get_natural_key_fields ( ) natural_key . extend ( [ name + '__' + nname for nname in nested_key ] ) return natural_key
Determine actual natural key field list, incorporating the natural keys
        of related objects as needed.