Split stdlib into Python 2 and 3 versions (#5442)

All new files in stdlib/@python2 are straight copies of the
corresponding files in stdlib.

stdlib/@python2/aifc.pyi

@@ -0,0 +1,88 @@
+import sys
+from types import TracebackType
+from typing import IO, Any, List, NamedTuple, Optional, Text, Tuple, Type, Union, overload
+from typing_extensions import Literal
+
+class Error(Exception): ...
+
+class _aifc_params(NamedTuple):
+    nchannels: int
+    sampwidth: int
+    framerate: int
+    nframes: int
+    comptype: bytes
+    compname: bytes
+
+_File = Union[Text, IO[bytes]]
+_Marker = Tuple[int, int, bytes]
+
+class Aifc_read:
+    def __init__(self, f: _File) -> None: ...
+    if sys.version_info >= (3, 4):
+        def __enter__(self) -> Aifc_read: ...
+        def __exit__(
+            self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
+        ) -> None: ...
+    def initfp(self, file: IO[bytes]) -> None: ...
+    def getfp(self) -> IO[bytes]: ...
+    def rewind(self) -> None: ...
+    def close(self) -> None: ...
+    def tell(self) -> int: ...
+    def getnchannels(self) -> int: ...
+    def getnframes(self) -> int: ...
+    def getsampwidth(self) -> int: ...
+    def getframerate(self) -> int: ...
+    def getcomptype(self) -> bytes: ...
+    def getcompname(self) -> bytes: ...
+    def getparams(self) -> _aifc_params: ...
+    def getmarkers(self) -> Optional[List[_Marker]]: ...
+    def getmark(self, id: int) -> _Marker: ...
+    def setpos(self, pos: int) -> None: ...
+    def readframes(self, nframes: int) -> bytes: ...
+
+class Aifc_write:
+    def __init__(self, f: _File) -> None: ...
+    def __del__(self) -> None: ...
+    if sys.version_info >= (3, 4):
+        def __enter__(self) -> Aifc_write: ...
+        def __exit__(
+            self, exc_type: Optional[Type[BaseException]], exc_val: Optional[BaseException], exc_tb: Optional[TracebackType]
+        ) -> None: ...
+    def initfp(self, file: IO[bytes]) -> None: ...
+    def aiff(self) -> None: ...
+    def aifc(self) -> None: ...
+    def setnchannels(self, nchannels: int) -> None: ...
+    def getnchannels(self) -> int: ...
+    def setsampwidth(self, sampwidth: int) -> None: ...
+    def getsampwidth(self) -> int: ...
+    def setframerate(self, framerate: int) -> None: ...
+    def getframerate(self) -> int: ...
+    def setnframes(self, nframes: int) -> None: ...
+    def getnframes(self) -> int: ...
+    def setcomptype(self, comptype: bytes, compname: bytes) -> None: ...
+    def getcomptype(self) -> bytes: ...
+    def getcompname(self) -> bytes: ...
+    def setparams(self, params: Tuple[int, int, int, int, bytes, bytes]) -> None: ...
+    def getparams(self) -> _aifc_params: ...
+    def setmark(self, id: int, pos: int, name: bytes) -> None: ...
+    def getmark(self, id: int) -> _Marker: ...
+    def getmarkers(self) -> Optional[List[_Marker]]: ...
+    def tell(self) -> int: ...
+    def writeframesraw(self, data: Any) -> None: ...  # Actual type for data is Buffer Protocol
+    def writeframes(self, data: Any) -> None: ...
+    def close(self) -> None: ...
+
+@overload
+def open(f: _File, mode: Literal["r", "rb"]) -> Aifc_read: ...
+@overload
+def open(f: _File, mode: Literal["w", "wb"]) -> Aifc_write: ...
+@overload
+def open(f: _File, mode: Optional[str] = ...) -> Any: ...
+
+if sys.version_info < (3, 9):
+    @overload
+    def openfp(f: _File, mode: Literal["r", "rb"]) -> Aifc_read: ...
+    @overload
+    def openfp(f: _File, mode: Literal["w", "wb"]) -> Aifc_write: ...
+    @overload
+    def openfp(f: _File, mode: Optional[str] = ...) -> Any: ...