def all_contents(self):
        for collection, _ in self.resolve():
            try:
                it = iter(collection)
            except TypeError:
                raise ConfigTypeError(
                    u'{0} must be an iterable, not {1}'.format(
                        self.name, type(collection).__name__
                    )
                )
            for value in it:
                yield value

    # Validation and conversion.
Iterates over all subviews from collections at this view from
dataset/ETHPy150Open beetbox/beets/beets/util/confit.py/ConfigView.all_contents