fix some abstract classes in Python 2 (#2240)

Part of #1476.

stdlib/2/__builtin__.pyi

@@ -1060,6 +1060,7 @@ class file(BinaryIO):
     @overload
     def __init__(self, file: int, mode: str = ..., buffering: int = ...) -> None: ...
     def __iter__(self) -> Iterator[str]: ...
+    def next(self) -> str: ...
     def read(self, n: int = ...) -> str: ...
     def __enter__(self) -> BinaryIO: ...
     def __exit__(self, t: Optional[type] = ..., exc: Optional[BaseException] = ..., tb: Optional[Any] = ...) -> bool: ...

stdlib/2/builtins.pyi

@@ -1060,6 +1060,7 @@ class file(BinaryIO):
     @overload
     def __init__(self, file: int, mode: str = ..., buffering: int = ...) -> None: ...
     def __iter__(self) -> Iterator[str]: ...
+    def next(self) -> str: ...
     def read(self, n: int = ...) -> str: ...
     def __enter__(self) -> BinaryIO: ...
     def __exit__(self, t: Optional[type] = ..., exc: Optional[BaseException] = ..., tb: Optional[Any] = ...) -> bool: ...

stdlib/2/cStringIO.pyi

@@ -1,12 +1,15 @@
 # Stubs for cStringIO (Python 2.7)
 # See https://docs.python.org/2/library/stringio.html
 
+from abc import ABCMeta
 from typing import overload, IO, List, Iterable, Iterator, Optional, Union
 from types import TracebackType
 
 # TODO the typing.IO[] generics should be split into input and output.
 
-class InputType(IO[str], Iterator[str]):
+# This class isn't actually abstract, but you can't instantiate it
+# directly, so we might as well treat it as abstract in the stub.
+class InputType(IO[str], Iterator[str], metaclass=ABCMeta):
     def getvalue(self) -> str: ...
     def close(self) -> None: ...
     @property
@@ -23,7 +26,8 @@ class InputType(IO[str], Iterator[str]):
     def next(self) -> str: ...
     def reset(self) -> None: ...
 
-class OutputType(IO[str], Iterator[str]):
+
+class OutputType(IO[str], Iterator[str], metaclass=ABCMeta):
     @property
     def softspace(self) -> int: ...
     def getvalue(self) -> str: ...

stdlib/2/typing.pyi

@@ -348,7 +348,7 @@ class TextIO(IO[unicode]):
     @abstractmethod
     def __enter__(self) -> TextIO: ...
 
-class ByteString(Sequence[int]): ...
+class ByteString(Sequence[int], metaclass=ABCMeta): ...
 
 class Match(Generic[AnyStr]):
     pos = 0

third_party/2/enum.pyi

@@ -15,6 +15,7 @@ class EnumMeta(ABCMeta, Iterable[Enum], Sized, Reversible[Enum], Container[Enum]
     def __getitem__(self: Type[_T], name: str) -> _T: ...
     @property
     def __members__(self: Type[_T]) -> Mapping[str, _T]: ...
+    def __len__(self) -> int: ...
 
 class Enum(metaclass=EnumMeta):
     def __new__(cls: Type[_T], value: Any) -> _T: ...