code: def directory_values_generator(self, key):
      '''Retrieve directory values for given key.'''
      directory = self.directory(key)
      for key in directory:
        yield self.get(Key(key)f directory_values_generator(self, key):
      '''Retrieve directory values for given key.'''
      directory = self.directory(key)
      for key in directory:
        yield self.get(Key(key))
docs: Retrieve directory values for given key.