[PyYAML] Complete parser function annotations (#16755)

Author: iamabhisheknag

stubs/PyYAML/yaml/__init__.pyi

@@ -28,10 +28,10 @@ __with_libyaml__: Final[bool]
 __version__: Final[str]
 
 def warnings(settings=None): ...
-def scan(stream, Loader: type[_Loader | _CLoader] = ...): ...
-def parse(stream, Loader: type[_Loader | _CLoader] = ...): ...
-def compose(stream, Loader: type[_Loader | _CLoader] = ...): ...
-def compose_all(stream, Loader: type[_Loader | _CLoader] = ...): ...
+def scan(stream: _ReadStream, Loader: type[_Loader | _CLoader] = ...) -> Iterator[Token]: ...
+def parse(stream: _ReadStream, Loader: type[_Loader | _CLoader] = ...) -> Iterator[Event]: ...
+def compose(stream: _ReadStream, Loader: type[_Loader | _CLoader] = ...) -> Node | None: ...
+def compose_all(stream: _ReadStream, Loader: type[_Loader | _CLoader] = ...) -> Iterator[Node]: ...
 def load(stream: _ReadStream, Loader: type[_Loader | _CLoader]) -> _YAMLObject: ...
 def load_all(stream: _ReadStream, Loader: type[_Loader | _CLoader]) -> Iterator[_YAMLObject]: ...
 def full_load(stream: _ReadStream) -> _YAMLObject: ...