1 files changed, 34 insertions, 3 deletions
diff --git a/wsgitools/internal.py b/wsgitools/internal.py
index 9bf7ded..86a9d5a 100644
--- a/wsgitools/internal.py
+++ b/wsgitools/internal.py
@@ -1,11 +1,42 @@
-def bytes2str(bstr):
+import sys
+import typing
+
+def bytes2str(bstr: bytes) -> str:
     assert isinstance(bstr, bytes)
     return bstr.decode("iso-8859-1") # always successful
 
-def str2bytes(sstr):
+def str2bytes(sstr: str) -> bytes:
     assert isinstance(sstr, str)
     return sstr.encode("iso-8859-1") # might fail, but spec says it doesn't
 
-def textopen(filename, mode):
+def textopen(filename: str, mode: str) -> typing.TextIO:
     # We use the same encoding as for all wsgi strings here.
     return open(filename, mode, encoding="iso-8859-1")
+
+Environ = typing.Dict[str, typing.Any]
+
+HeaderList = typing.List[typing.Tuple[str, str]]
+
+if sys.version_info >= (3, 11):
+    OptExcInfo = typing.Optional[
+        typing.Tuple[type[BaseException], BaseException, typing.Any]
+    ]
+else:
+    OptExcInfo = typing.Optional[
+        typing.Tuple[typing.Any, BaseException, typing.Any]
+    ]
+
+WriteCallback = typing.Callable[[bytes], None]
+
+if sys.version_info >= (3, 11):
+    class StartResponse(typing.Protocol):
+        def __call__(
+            self, status: str, headers: HeaderList, exc_info: OptExcInfo = None
+        ) -> WriteCallback:
+            ...
+else:
+    StartResponse = typing.Callable[
+        [str, HeaderList, OptExcInfo], WriteCallback
+    ]
+
+WsgiApp = typing.Callable[[Environ, StartResponse], typing.Iterable[bytes]]