Introduce VAnnotation

Author: Tinche

Diff for: src/cattrs/v/__init__.py

@@ -1,5 +1,7 @@
 """Cattrs validation."""
-from typing import Callable, List, Union
+from typing import Any, Callable, List, Union
+
+from attrs import frozen
 
 from .._compat import ExceptionGroup
 from ..errors import (
@@ -31,6 +33,13 @@
 ]
 
 
+@frozen
+class VAnnotation:
+    """Use this with Annotated to get validation."""
+
+    validators: tuple[Callable[[Any], Any]]
+
+
 def format_exception(exc: BaseException, type: Union[type, None]) -> str:
     """The default exception formatter, handling the most common exceptions.