fix the StartResponse type and make it a protocol

1 files changed, 13 insertions, 2 deletions

diff --git a/paste/__init__.py b/paste/__init__.py
index 9b052c6..31f86bc 100644
--- a/paste/__init__.py
+++ b/paste/__init__.py
@@ -1,7 +1,7 @@
 from base64 import b64decode, b64encode
 from functools import wraps
 from wsgiref.util import request_uri
-from typing import Optional, Any
+from typing import Optional, Any, Protocol
 from collections.abc import Callable, Iterable
 import binascii
 import traceback
@@ -10,7 +10,18 @@ from sqlite3 import Connection
 from . import db
 from . import store
 
-StartResponse = Callable[[str, list[tuple[str, str]]], Optional[tuple]]
+
+class StartResponse(Protocol):
+    def __call__(
+        self,
+        status: str,
+        headers: list[tuple[str, str]],
+        exc_info: Optional[tuple] = ...,
+        /,
+    ) -> Callable[[bytes], object]:
+        ...
+
+
 Env = dict[str, Any]
 App = Callable[[Env, StartResponse], Iterable[bytes]]
 Response = Iterable[bytes]