src/transformers/models/bart/configuration_bart.py/BartOnnxConfig/_flatten_past_key_values_
class BartOnnxConfig:    def _flatten_past_key_values_(self, flattened_output, name, idx, t):
        if self.task in ["default", "seq2seq-lm"]:
            flattened_output = super()._flatten_past_key_values_(flattened_output, name, idx, t)
        else:
            flattened_output = super(OnnxSeq2SeqConfigWithPast, self)._flatten_past_key_values_(
                flattened_output, name, idx, t
            )