python · AlexWaygood · May 16, 2026
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
@@ -27,7 +27,7 @@ repos:
           - "--unsafe-fixes"
         files: '.*test_cases/.+\.py$'
   - repo: https://github.com/psf/black-pre-commit-mirror
-    rev: 26.3.1
+    rev: 26.5.0
     hooks:
       - id: black
   - repo: https://github.com/pycqa/flake8

diff --git a/pyproject.toml b/pyproject.toml
@@ -9,6 +9,7 @@ requires-python = ">=3.10" # Minimum version to run tests, used by uv run
 line-length = 130
 target-version = ["py310"]
 skip-magic-trailing-comma = true
+preview = true
 
 [tool.ruff]
 line-length = 130

diff --git a/stdlib/_asyncio.pyi b/stdlib/_asyncio.pyi
@@ -16,10 +16,12 @@ class Future(Awaitable[_T]):
     @property
     def _exception(self) -> BaseException | None: ...
     _blocking: bool
+
     @property
     def _log_traceback(self) -> bool: ...
     @_log_traceback.setter
     def _log_traceback(self, val: Literal[False]) -> None: ...
+
     _asyncio_future_blocking: bool  # is a part of duck-typing contract for `Future`
     def __init__(self, *, loop: AbstractEventLoop | None = None) -> None: ...
     def __del__(self) -> None: ...

diff --git a/stdlib/_bisect.pyi b/stdlib/_bisect.pyi
@@ -38,6 +38,7 @@ def bisect_left(
 def bisect_left(
     a: SupportsGetItem[int, _T], x: SupportsRichComparisonT, lo: int = 0, *, hi: int, key: Callable[[_T], SupportsRichComparisonT]
 ) -> int: ...
+
 @overload
 def bisect_right(
     a: SupportsLenAndGetItem[SupportsRichComparisonT],
@@ -72,6 +73,7 @@ def bisect_right(
 def bisect_right(
     a: SupportsGetItem[int, _T], x: SupportsRichComparisonT, lo: int = 0, *, hi: int, key: Callable[[_T], SupportsRichComparisonT]
 ) -> int: ...
+
 @overload
 def insort_left(
     a: MutableSequence[SupportsRichComparisonT],
@@ -85,6 +87,7 @@ def insort_left(
 def insort_left(
     a: MutableSequence[_T], x: _T, lo: int = 0, hi: int | None = None, *, key: Callable[[_T], SupportsRichComparisonT]
 ) -> None: ...
+
 @overload
 def insort_right(
     a: MutableSequence[SupportsRichComparisonT],

diff --git a/stdlib/_codecs.pyi b/stdlib/_codecs.pyi
@@ -49,6 +49,7 @@ def encode(obj: ReadableBuffer, encoding: _BytesToBytesEncoding, errors: str = "
 def encode(obj: str, encoding: _StrToStrEncoding, errors: str = "strict") -> str: ...  # type: ignore[overload-overlap]
 @overload
 def encode(obj: str, encoding: str = "utf-8", errors: str = "strict") -> bytes: ...
+
 @overload
 def decode(obj: ReadableBuffer, encoding: _BytesToBytesEncoding, errors: str = "strict") -> bytes: ...  # type: ignore[overload-overlap]
 @overload
@@ -67,6 +68,7 @@ def decode(
 def decode(obj: str, encoding: Literal["hex", "hex_codec"], errors: str = "strict") -> bytes: ...
 @overload
 def decode(obj: ReadableBuffer, encoding: str = "utf-8", errors: str = "strict") -> str: ...
+
 def lookup(encoding: str, /) -> codecs.CodecInfo: ...
 def charmap_build(map: str, /) -> _CharMap: ...
 def ascii_decode(data: ReadableBuffer, errors: str | None = None, /) -> tuple[str, int]: ...

diff --git a/stdlib/_contextvars.pyi b/stdlib/_contextvars.pyi
@@ -14,15 +14,18 @@ class ContextVar(Generic[_T]):
     def __new__(cls, name: str) -> Self: ...
     @overload
     def __new__(cls, name: str, *, default: _T) -> Self: ...
+
     def __hash__(self) -> int: ...
     @property
     def name(self) -> str: ...
+
     @overload
     def get(self) -> _T: ...
     @overload
     def get(self, default: _T, /) -> _T: ...
     @overload
     def get(self, default: _D, /) -> _D | _T: ...
+
     def set(self, value: _T, /) -> Token[_T]: ...
     def reset(self, token: Token[_T], /) -> None: ...
     def __class_getitem__(cls, item: Any, /) -> GenericAlias: ...
@@ -49,12 +52,14 @@ def copy_context() -> Context: ...
 @final
 class Context(Mapping[ContextVar[Any], Any]):
     def __init__(self) -> None: ...
+
     @overload
     def get(self, key: ContextVar[_T], default: None = None, /) -> _T | None: ...
     @overload
     def get(self, key: ContextVar[_T], default: _T, /) -> _T: ...
     @overload
     def get(self, key: ContextVar[_T], default: _D, /) -> _T | _D: ...
+
     def run(self, callable: Callable[_P, _T], *args: _P.args, **kwargs: _P.kwargs) -> _T: ...
     def copy(self) -> Context: ...
     __hash__: ClassVar[None]  # type: ignore[assignment]

diff --git a/stdlib/_ctypes.pyi b/stdlib/_ctypes.pyi
@@ -127,21 +127,25 @@ class _PyCPointerType(_CTypeBaseType):
 class _Pointer(_PointerLike, _CData, Generic[_CT], metaclass=_PyCPointerType):
     _type_: type[_CT]
     contents: _CT
+
     @overload
     def __init__(self) -> None: ...
     @overload
     def __init__(self, arg: _CT) -> None: ...
+
     @overload
     def __getitem__(self, key: int, /) -> Any: ...
     @overload
     def __getitem__(self, key: slice[SupportsIndex | None], /) -> list[Any]: ...
+
     def __setitem__(self, key: int, value: Any, /) -> None: ...
 
 if sys.version_info < (3, 14):
     @overload
     def POINTER(type: None, /) -> type[c_void_p]: ...
     @overload
     def POINTER(type: type[_CT], /) -> type[_Pointer[_CT]]: ...
+
     def pointer(obj: _CT, /) -> _Pointer[_CT]: ...
 
 # This class is not exposed. It calls itself _ctypes.CArgObject.
@@ -177,6 +181,7 @@ class CFuncPtr(_PointerLike, _CData, metaclass=_PyCFuncPtrType):
     errcheck: _ECT
     # Abstract attribute that must be defined on subclasses
     _flags_: ClassVar[int]
+
     @overload
     def __new__(cls) -> Self: ...
     @overload
@@ -209,10 +214,12 @@ if sys.version_info >= (3, 14):
         bit_offset: int
         bit_size: int
         is_anonymous: bool
+
         @overload
         def __get__(self, instance: None, owner: builtins.type[Any] | None = None, /) -> Self: ...
         @overload
         def __get__(self, instance: Any, owner: builtins.type[Any] | None = None, /) -> _GetT: ...
+
         def __set__(self, instance: Any, value: _SetT, /) -> None: ...
 
     _CField = CField
@@ -223,10 +230,12 @@ else:
     class _CField(Generic[_CT, _GetT, _SetT]):
         offset: int
         size: int
+
         @overload
         def __get__(self, instance: None, owner: type[Any] | None = None, /) -> Self: ...
         @overload
         def __get__(self, instance: Any, owner: type[Any] | None = None, /) -> _GetT: ...
+
         def __set__(self, instance: Any, value: _SetT, /) -> None: ...
 
 # This class is not exposed. It calls itself _ctypes.UnionType.
@@ -308,16 +317,19 @@ class Array(_CData, Generic[_CT], metaclass=_PyCArrayType):
     def _length_(self) -> int: ...
     @_length_.setter
     def _length_(self, value: int) -> None: ...
+
     @property
     @abstractmethod
     def _type_(self) -> type[_CT]: ...
     @_type_.setter
     def _type_(self, value: type[_CT]) -> None: ...
+
     # Note: only available if _CT == c_char
     @property
     def raw(self) -> bytes: ...
     @raw.setter
     def raw(self, value: ReadableBuffer) -> None: ...
+
     value: Any  # Note: bytes if _CT == c_char, str if _CT == c_wchar, unavailable otherwise
     # TODO: These methods cannot be annotated correctly at the moment.
     # All of these "Any"s stand for the array's element type, but it's not possible to use _CT
@@ -332,14 +344,17 @@ class Array(_CData, Generic[_CT], metaclass=_PyCArrayType):
     # This special behavior is not easy to model in a stub, so for now all places where
     # the array element type would belong are annotated with Any instead.
     def __init__(self, *args: Any) -> None: ...
+
     @overload
     def __getitem__(self, key: int, /) -> Any: ...
     @overload
     def __getitem__(self, key: slice[SupportsIndex | None], /) -> list[Any]: ...
+
     @overload
     def __setitem__(self, key: int, value: Any, /) -> None: ...
     @overload
     def __setitem__(self, key: slice[SupportsIndex | None], value: Iterable[Any], /) -> None: ...
+
     def __iter__(self) -> Iterator[Any]: ...
     # Can't inherit from Sized because the metaclass conflict between
     # Sized and _CData prevents using _CDataMeta.

diff --git a/stdlib/_curses.pyi b/stdlib/_curses.pyi
@@ -375,18 +375,22 @@ class error(Exception): ...
 @final
 class window:  # undocumented
     encoding: str
+
     @overload
     def addch(self, ch: _ChType, attr: int = ...) -> None: ...
     @overload
     def addch(self, y: int, x: int, ch: _ChType, attr: int = ...) -> None: ...
+
     @overload
     def addnstr(self, str: str, n: int, attr: int = ...) -> None: ...
     @overload
     def addnstr(self, y: int, x: int, str: str, n: int, attr: int = ...) -> None: ...
+
     @overload
     def addstr(self, str: str, attr: int = ...) -> None: ...
     @overload
     def addstr(self, y: int, x: int, str: str, attr: int = ...) -> None: ...
+
     def attroff(self, attr: int, /) -> None: ...
     def attron(self, attr: int, /) -> None: ...
     def attrset(self, attr: int, /) -> None: ...
@@ -403,10 +407,12 @@ class window:  # undocumented
         bl: _ChType = ...,
         br: _ChType = ...,
     ) -> None: ...
+
     @overload
     def box(self) -> None: ...
     @overload
     def box(self, vertch: _ChType = 0, horch: _ChType = 0) -> None: ...
+
     @overload
     def chgat(self, attr: int) -> None: ...
     @overload
@@ -415,39 +421,49 @@ class window:  # undocumented
     def chgat(self, y: int, x: int, attr: int) -> None: ...
     @overload
     def chgat(self, y: int, x: int, num: int, attr: int) -> None: ...
+
     def clear(self) -> None: ...
     def clearok(self, yes: int) -> None: ...
     def clrtobot(self) -> None: ...
     def clrtoeol(self) -> None: ...
     def cursyncup(self) -> None: ...
+
     @overload
     def delch(self) -> None: ...
     @overload
     def delch(self, y: int, x: int) -> None: ...
+
     def deleteln(self) -> None: ...
+
     @overload
     def derwin(self, begin_y: int, begin_x: int) -> window: ...
     @overload
     def derwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+
     def echochar(self, ch: _ChType, attr: int = 0, /) -> None: ...
     def enclose(self, y: int, x: int, /) -> bool: ...
     def erase(self) -> None: ...
     def getbegyx(self) -> tuple[int, int]: ...
     def getbkgd(self) -> tuple[int, int]: ...
+
     @overload
     def getch(self) -> int: ...
     @overload
     def getch(self, y: int, x: int) -> int: ...
+
     @overload
     def get_wch(self) -> int | str: ...
     @overload
     def get_wch(self, y: int, x: int) -> int | str: ...
+
     @overload
     def getkey(self) -> str: ...
     @overload
     def getkey(self, y: int, x: int) -> str: ...
+
     def getmaxyx(self) -> tuple[int, int]: ...
     def getparyx(self) -> tuple[int, int]: ...
+
     @overload
     def getstr(self) -> bytes: ...
     @overload
@@ -456,36 +472,46 @@ class window:  # undocumented
     def getstr(self, y: int, x: int) -> bytes: ...
     @overload
     def getstr(self, y: int, x: int, n: int) -> bytes: ...
+
     def getyx(self) -> tuple[int, int]: ...
+
     @overload
     def hline(self, ch: _ChType, n: int) -> None: ...
     @overload
     def hline(self, y: int, x: int, ch: _ChType, n: int) -> None: ...
+
     def idcok(self, flag: bool) -> None: ...
     def idlok(self, yes: bool) -> None: ...
     def immedok(self, flag: bool) -> None: ...
+
     @overload
     def inch(self) -> int: ...
     @overload
     def inch(self, y: int, x: int) -> int: ...
+
     @overload
     def insch(self, ch: _ChType, attr: int = ...) -> None: ...
     @overload
     def insch(self, y: int, x: int, ch: _ChType, attr: int = ...) -> None: ...
+
     def insdelln(self, nlines: int) -> None: ...
     def insertln(self) -> None: ...
+
     @overload
     def insnstr(self, str: str, n: int, attr: int = ...) -> None: ...
     @overload
     def insnstr(self, y: int, x: int, str: str, n: int, attr: int = ...) -> None: ...
+
     @overload
     def insstr(self, str: str, attr: int = ...) -> None: ...
     @overload
     def insstr(self, y: int, x: int, str: str, attr: int = ...) -> None: ...
+
     @overload
     def instr(self, n: int = 2047) -> bytes: ...
     @overload
     def instr(self, y: int, x: int, n: int = 2047) -> bytes: ...
+
     def is_linetouched(self, line: int, /) -> bool: ...
     def is_wintouched(self) -> bool: ...
     def keypad(self, yes: bool, /) -> None: ...
@@ -495,50 +521,60 @@ class window:  # undocumented
     def mvwin(self, new_y: int, new_x: int) -> None: ...
     def nodelay(self, yes: bool) -> None: ...
     def notimeout(self, yes: bool) -> None: ...
+
     @overload
     def noutrefresh(self) -> None: ...
     @overload
     def noutrefresh(self, pminrow: int, pmincol: int, sminrow: int, smincol: int, smaxrow: int, smaxcol: int) -> None: ...
+
     @overload
     def overlay(self, destwin: window) -> None: ...
     @overload
     def overlay(
         self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
+
     @overload
     def overwrite(self, destwin: window) -> None: ...
     @overload
     def overwrite(
         self, destwin: window, sminrow: int, smincol: int, dminrow: int, dmincol: int, dmaxrow: int, dmaxcol: int
     ) -> None: ...
+
     def putwin(self, file: SupportsWrite[bytes], /) -> None: ...
     def redrawln(self, beg: int, num: int, /) -> None: ...
     def redrawwin(self) -> None: ...
+
     @overload
     def refresh(self) -> None: ...
     @overload
     def refresh(self, pminrow: int, pmincol: int, sminrow: int, smincol: int, smaxrow: int, smaxcol: int) -> None: ...
+
     def resize(self, nlines: int, ncols: int) -> None: ...
     def scroll(self, lines: int = 1) -> None: ...
     def scrollok(self, flag: bool) -> None: ...
     def setscrreg(self, top: int, bottom: int, /) -> None: ...
     def standend(self) -> None: ...
     def standout(self) -> None: ...
+
     @overload
     def subpad(self, begin_y: int, begin_x: int) -> window: ...
     @overload
     def subpad(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+
     @overload
     def subwin(self, begin_y: int, begin_x: int) -> window: ...
     @overload
     def subwin(self, nlines: int, ncols: int, begin_y: int, begin_x: int) -> window: ...
+
     def syncdown(self) -> None: ...
     def syncok(self, flag: bool) -> None: ...
     def syncup(self) -> None: ...
     def timeout(self, delay: int) -> None: ...
     def touchline(self, start: int, count: int, changed: bool = True) -> None: ...
     def touchwin(self) -> None: ...
     def untouchwin(self) -> None: ...
+
     @overload
     def vline(self, ch: _ChType, n: int) -> None: ...
     @overload