Updates

ETB-API/venv/lib/python3.12/site-packages/referencing/_attrs.py

@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+from typing import NoReturn, TypeVar
+
+from attrs import define as _define, frozen as _frozen
+
+_T = TypeVar("_T")
+
+
+def define(cls: type[_T]) -> type[_T]:  # pragma: no cover
+    cls.__init_subclass__ = _do_not_subclass
+    return _define(cls)
+
+
+def frozen(cls: type[_T]) -> type[_T]:
+    cls.__init_subclass__ = _do_not_subclass
+    return _frozen(cls)
+
+
+class UnsupportedSubclassing(Exception):
+    def __str__(self):
+        return (
+            "Subclassing is not part of referencing's public API. "
+            "If no other suitable API exists for what you're trying to do, "
+            "feel free to file an issue asking for one."
+        )
+
+
+@staticmethod
+def _do_not_subclass() -> NoReturn:  # pragma: no cover
+    raise UnsupportedSubclassing()