def METHOD_NAME(self, async_mode: bool) -> str:
    key = (
        "sync_mixin_typing_definitions"
        if async_mode
        else "async_mixin_typing_definitions"
    )
    origin = "".join(
        [
            metadata_json.get("operation_mixins", {}).get(key, "")
            for metadata_json in self.version_path_to_metadata.values()
        ]
    )
    return "\n".join(set(origin.split("\n")))