    def get_feature_names(self) -> Tuple[str, ...]:
        """
        Returns the feature names, in order, i.e. the keys of the ordered output
        dictionary from `.forward()`.
        """
        raise NotImplementedError()
Returns the feature names, in order, i.e. the keys of the ordered output
dictionary from `.forward()`.
allennlp/modules/vision/grid_embedder.py