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/pickle.pyi

@@ -0,0 +1,186 @@
+import sys
+from typing import IO, Any, Callable, Iterable, Iterator, Mapping, Optional, Tuple, Type, Union
+
+HIGHEST_PROTOCOL: int
+if sys.version_info >= (3, 0):
+    DEFAULT_PROTOCOL: int
+
+bytes_types: Tuple[Type[Any], ...]  # undocumented
+
+if sys.version_info >= (3, 8):
+    # TODO: holistic design for buffer interface (typing.Buffer?)
+    class PickleBuffer:
+        # buffer must be a buffer-providing object
+        def __init__(self, buffer: Any) -> None: ...
+        def raw(self) -> memoryview: ...
+        def release(self) -> None: ...
+    _BufferCallback = Optional[Callable[[PickleBuffer], Any]]
+    def dump(
+        obj: Any,
+        file: IO[bytes],
+        protocol: Optional[int] = ...,
+        *,
+        fix_imports: bool = ...,
+        buffer_callback: _BufferCallback = ...,
+    ) -> None: ...
+    def dumps(
+        obj: Any, protocol: Optional[int] = ..., *, fix_imports: bool = ..., buffer_callback: _BufferCallback = ...
+    ) -> bytes: ...
+    def load(
+        file: IO[bytes],
+        *,
+        fix_imports: bool = ...,
+        encoding: str = ...,
+        errors: str = ...,
+        buffers: Optional[Iterable[Any]] = ...,
+    ) -> Any: ...
+    def loads(
+        __data: bytes, *, fix_imports: bool = ..., encoding: str = ..., errors: str = ..., buffers: Optional[Iterable[Any]] = ...
+    ) -> Any: ...
+
+elif sys.version_info >= (3, 0):
+    def dump(obj: Any, file: IO[bytes], protocol: Optional[int] = ..., *, fix_imports: bool = ...) -> None: ...
+    def dumps(obj: Any, protocol: Optional[int] = ..., *, fix_imports: bool = ...) -> bytes: ...
+    def load(file: IO[bytes], *, fix_imports: bool = ..., encoding: str = ..., errors: str = ...) -> Any: ...
+    def loads(data: bytes, *, fix_imports: bool = ..., encoding: str = ..., errors: str = ...) -> Any: ...
+
+else:
+    def dump(obj: Any, file: IO[bytes], protocol: Optional[int] = ...) -> None: ...
+    def dumps(obj: Any, protocol: Optional[int] = ...) -> bytes: ...
+    def load(file: IO[bytes]) -> Any: ...
+    def loads(string: bytes) -> Any: ...
+
+class PickleError(Exception): ...
+class PicklingError(PickleError): ...
+class UnpicklingError(PickleError): ...
+
+_reducedtype = Union[
+    str,
+    Tuple[Callable[..., Any], Tuple[Any, ...]],
+    Tuple[Callable[..., Any], Tuple[Any, ...], Any],
+    Tuple[Callable[..., Any], Tuple[Any, ...], Any, Optional[Iterator[Any]]],
+    Tuple[Callable[..., Any], Tuple[Any, ...], Any, Optional[Iterator[Any]], Optional[Iterator[Any]]],
+]
+
+class Pickler:
+    fast: bool
+    if sys.version_info >= (3, 3):
+        dispatch_table: Mapping[type, Callable[[Any], _reducedtype]]
+
+    if sys.version_info >= (3, 8):
+        def __init__(
+            self,
+            file: IO[bytes],
+            protocol: Optional[int] = ...,
+            *,
+            fix_imports: bool = ...,
+            buffer_callback: _BufferCallback = ...,
+        ) -> None: ...
+        def reducer_override(self, obj: Any) -> Any: ...
+    elif sys.version_info >= (3, 0):
+        def __init__(self, file: IO[bytes], protocol: Optional[int] = ..., *, fix_imports: bool = ...) -> None: ...
+    else:
+        def __init__(self, file: IO[bytes], protocol: Optional[int] = ...) -> None: ...
+    def dump(self, __obj: Any) -> None: ...
+    def clear_memo(self) -> None: ...
+    def persistent_id(self, obj: Any) -> Any: ...
+
+class Unpickler:
+    if sys.version_info >= (3, 8):
+        def __init__(
+            self,
+            file: IO[bytes],
+            *,
+            fix_imports: bool = ...,
+            encoding: str = ...,
+            errors: str = ...,
+            buffers: Optional[Iterable[Any]] = ...,
+        ) -> None: ...
+    elif sys.version_info >= (3, 0):
+        def __init__(self, file: IO[bytes], *, fix_imports: bool = ..., encoding: str = ..., errors: str = ...) -> None: ...
+    else:
+        def __init__(self, file: IO[bytes]) -> None: ...
+    def load(self) -> Any: ...
+    def find_class(self, __module_name: str, __global_name: str) -> Any: ...
+    if sys.version_info >= (3, 0):
+        def persistent_load(self, pid: Any) -> Any: ...
+
+MARK: bytes
+STOP: bytes
+POP: bytes
+POP_MARK: bytes
+DUP: bytes
+FLOAT: bytes
+INT: bytes
+BININT: bytes
+BININT1: bytes
+LONG: bytes
+BININT2: bytes
+NONE: bytes
+PERSID: bytes
+BINPERSID: bytes
+REDUCE: bytes
+STRING: bytes
+BINSTRING: bytes
+SHORT_BINSTRING: bytes
+UNICODE: bytes
+BINUNICODE: bytes
+APPEND: bytes
+BUILD: bytes
+GLOBAL: bytes
+DICT: bytes
+EMPTY_DICT: bytes
+APPENDS: bytes
+GET: bytes
+BINGET: bytes
+INST: bytes
+LONG_BINGET: bytes
+LIST: bytes
+EMPTY_LIST: bytes
+OBJ: bytes
+PUT: bytes
+BINPUT: bytes
+LONG_BINPUT: bytes
+SETITEM: bytes
+TUPLE: bytes
+EMPTY_TUPLE: bytes
+SETITEMS: bytes
+BINFLOAT: bytes
+
+TRUE: bytes
+FALSE: bytes
+
+# protocol 2
+PROTO: bytes
+NEWOBJ: bytes
+EXT1: bytes
+EXT2: bytes
+EXT4: bytes
+TUPLE1: bytes
+TUPLE2: bytes
+TUPLE3: bytes
+NEWTRUE: bytes
+NEWFALSE: bytes
+LONG1: bytes
+LONG4: bytes
+
+if sys.version_info >= (3, 0):
+    # protocol 3
+    BINBYTES: bytes
+    SHORT_BINBYTES: bytes
+
+if sys.version_info >= (3, 4):
+    # protocol 4
+    SHORT_BINUNICODE: bytes
+    BINUNICODE8: bytes
+    BINBYTES8: bytes
+    EMPTY_SET: bytes
+    ADDITEMS: bytes
+    FROZENSET: bytes
+    NEWOBJ_EX: bytes
+    STACK_GLOBAL: bytes
+    MEMOIZE: bytes
+    FRAME: bytes
+
+def encode_long(x: int) -> bytes: ...  # undocumented
+def decode_long(data: bytes) -> int: ...  # undocumented