def get_unique(self) -> list[T_PandasOrXarrayIndex]:
        """Return a list of unique indexes, preserving order."""

        unique_indexes: list[T_PandasOrXarrayIndex] = []
        seen: set[int] = set()

        for index in self._indexes.values():
            index_id = id(index)
            if index_id not in seen:
                unique_indexes.append(index)
                seen.add(index_id)

        return unique_indexes
Return a list of unique indexes, preserving order.
xarray/core/indexes.py