def _make_key(self):
        """Make a key for caching files in the LRU cache."""
        value = (
            self._opener,
            self._args,
            "a" if self._mode == "w" else self._mode,
            tuple(sorted(self._kwargs.items())),
            self._manager_id,
        )
        return _HashedSequence(value)
Make a key for caching files in the LRU cache.
xarray/backends/file_manager.py