Mark stub-only private symbols as @type_check_only in third-party stubs (#14545)

stubs/Markdown/markdown/extensions/toc.pyi

@@ -1,6 +1,6 @@
 from collections.abc import Iterator, MutableSet
 from re import Pattern
-from typing import Any, TypedDict
+from typing import Any, TypedDict, type_check_only
 from typing_extensions import deprecated
 from xml.etree.ElementTree import Element
 
@@ -10,11 +10,13 @@ from markdown.treeprocessors import Treeprocessor
 
 IDCOUNT_RE: Pattern[str]
 
+@type_check_only
 class _FlatTocToken(TypedDict):
     level: int
     id: str
     name: str
 
+@type_check_only
 class _TocToken(_FlatTocToken):
     children: list[_TocToken]
 

stubs/Markdown/markdown/util.pyi

@@ -1,7 +1,7 @@
 import sys
 from collections.abc import Iterator
 from re import Pattern
-from typing import Final, Generic, TypedDict, TypeVar, overload
+from typing import Final, Generic, TypedDict, TypeVar, overload, type_check_only
 
 from markdown.core import Markdown
 
@@ -40,6 +40,7 @@ class Processor:
     md: Markdown
     def __init__(self, md: Markdown | None = None) -> None: ...
 
+@type_check_only
 class _TagData(TypedDict):
     tag: str
     attrs: dict[str, str]