From c8db1d6cfe55b8dd1627682f1c23a8476c8267c2 Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Tue, 29 Oct 2024 11:45:42 +0000
Subject: [PATCH] typing

---
 src/textual/css/stylesheet.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/textual/css/stylesheet.py b/src/textual/css/stylesheet.py
index 91076020db..dd321a2fa4 100644
--- a/src/textual/css/stylesheet.py
+++ b/src/textual/css/stylesheet.py
@@ -5,7 +5,7 @@
 from itertools import chain
 from operator import itemgetter
 from pathlib import Path, PurePath
-from typing import Iterable, NamedTuple, Sequence, cast
+from typing import Final, Iterable, NamedTuple, Sequence, cast
 
 import rich.repr
 from rich.console import Console, ConsoleOptions, RenderableType, RenderResult
@@ -435,7 +435,7 @@ def _check_rule(
 
     # pseudo classes which iterate over multiple nodes
     # These shouldn't be used in a cache key
-    EXCLUDE_PSEUDO_CLASSES_FROM_CACHE = {
+    _EXCLUDE_PSEUDO_CLASSES_FROM_CACHE: Final[set[str]] = {
         "first-of-type",
         "last-of_type",
         "odd",
@@ -488,7 +488,7 @@ def apply(
         cache_key: tuple | None = None
 
         if cache is not None and all_pseudo_classes.isdisjoint(
-            self.EXCLUDE_PSEUDO_CLASSES_FROM_CACHE
+            self._EXCLUDE_PSEUDO_CLASSES_FROM_CACHE
         ):
             cache_key = (
                 node._parent,