Markdown: use I/O protocols (#7851)

stubs/Markdown/markdown/core.pyi

@@ -1,6 +1,6 @@
 from _typeshed import Self
 from collections.abc import Callable, Mapping, Sequence
-from typing import Any, BinaryIO, ClassVar, TextIO
+from typing import Any, ClassVar, Protocol
 from typing_extensions import Literal
 from xml.etree.ElementTree import Element
 
@@ -8,6 +8,18 @@ from .blockparser import BlockParser
 from .extensions import Extension
 from .util import HtmlStash, Registry
 
+# TODO: The following protocols can be replaced by their counterparts from
+# codecs, once they have been propagated to all type checkers.
+class _WritableStream(Protocol):
+    def write(self, __data: bytes) -> object: ...
+    def seek(self, __offset: int, __whence: int) -> object: ...
+    def close(self) -> object: ...
+
+class _ReadableStream(Protocol):
+    def read(self, __size: int = ...) -> bytes: ...
+    def seek(self, __offset: int, __whence: int) -> object: ...
+    def close(self) -> object: ...
+
 class Markdown:
     preprocessors: Registry
     inlinePatterns: Registry
@@ -37,10 +49,7 @@ class Markdown:
     def is_block_level(self, tag: str) -> bool: ...
     def convert(self, source: str) -> str: ...
     def convertFile(
-        self,
-        input: str | TextIO | BinaryIO | None = ...,
-        output: str | TextIO | BinaryIO | None = ...,
-        encoding: str | None = ...,
+        self, input: str | _ReadableStream | None = ..., output: str | _WritableStream | None = ..., encoding: str | None = ...
     ) -> Markdown: ...
 
 def markdown(
@@ -53,8 +62,8 @@ def markdown(
 ) -> str: ...
 def markdownFromFile(
     *,
-    input: str | TextIO | BinaryIO | None = ...,
-    output: str | TextIO | BinaryIO | None = ...,
+    input: str | _ReadableStream | None = ...,
+    output: str | _WritableStream | None = ...,
     encoding: str | None = ...,
     extensions: Sequence[str | Extension] | None = ...,
     extension_configs: Mapping[str, Mapping[str, Any]] | None = ...,