From f66d0e587960e501ed5952d518ac67be3cc3d91c Mon Sep 17 00:00:00 2001
From: Angus Hollands <goosey15@gmail.com>
Date: Fri, 23 Jun 2023 10:00:57 +0100
Subject: [PATCH] fix: use `Union` instead of `|`

---
 myst_nb/core/config.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/myst_nb/core/config.py b/myst_nb/core/config.py
index e2e1cf7b..9ea0c0aa 100644
--- a/myst_nb/core/config.py
+++ b/myst_nb/core/config.py
@@ -1,7 +1,7 @@
 """Configuration for myst-nb."""
 import dataclasses as dc
 from enum import Enum
-from typing import Any, Callable, Iterable, Sequence
+from typing import Any, Callable, Iterable, Sequence, Union
 
 from myst_parser.config.dc_validators import (
     ValidatorType,
@@ -378,7 +378,7 @@ def __post_init__(self):
         },
         repr=False,
     )
-    mime_priority_overrides: Sequence[tuple[str, str, int | None]] = dc.field(
+    mime_priority_overrides: Sequence[tuple[str, str, Union[int, None]]] = dc.field(
         default=(),
         metadata={
             "validator": deep_iterable(