keras/src/layers/preprocessing/string_lookup.py/StringLookup/get_config
class StringLookup:    def get_config(self):
        config = {"encoding": self.encoding}
        base_config = super().get_config()
        # There is only one valid dtype for strings, so we don't expose this.
        del base_config["vocabulary_dtype"]
        return {**base_config, **config}