or None

src/textual/_types.py

@@ -1,8 +1,7 @@
 from typing import TYPE_CHECKING, Awaitable, Callable, List, Union
 
-from typing_extensions import Protocol
-
 from rich.segment import Segment
+from typing_extensions import Protocol
 
 if TYPE_CHECKING:
     from .message import Message

src/textual/css/_help_text.py

@@ -126,7 +126,10 @@ def _spacing_examples(property_name: str) -> ContextSpecificBullets:
 
 
 def property_invalid_value_help_text(
-    property_name: str, context: StylingContext, *, suggested_property_name: str = None
+    property_name: str,
+    context: StylingContext,
+    *,
+    suggested_property_name: str | None = None,
 ) -> HelpText:
     """Help text to show when the user supplies an invalid value for CSS property
     property.
@@ -301,7 +304,7 @@ def color_property_help_text(
     property_name: str,
     context: StylingContext,
     *,
-    error: Exception = None,
+    error: Exception | None = None,
 ) -> HelpText:
     """Help text to show when the user supplies an invalid value for a color
     property. For example, an unparseable color string.

src/textual/css/constants.py

@@ -5,7 +5,6 @@ from ..geometry import Spacing
 
 if typing.TYPE_CHECKING:
     from typing_extensions import Final
-    from .types import EdgeType
 
 VALID_VISIBILITY: Final = {"visible", "hidden"}
 VALID_DISPLAY: Final = {"block", "none"}