src/transformers/models/gpt2/configuration_gpt2.py/GPT2OnnxConfig/inputs
class GPT2OnnxConfig:    def inputs(self) -> Mapping[str, Mapping[int, str]]:
        common_inputs = OrderedDict({"input_ids": {0: "batch"}})
        if self.use_past:
            for i in range(self._config.n_layer * 2):
                common_inputs[f"past_key_values.{i}"] = {0: "batch", 2: "sequence"}

            common_inputs["attention_mask"] = {0: "batch", 1: "sequence"}
        else:
            common_inputs["attention_mask"] = {0: "batch", 1: "sequence"}

        return common_inputs