Move 2.7 to 2 (#635)

Closes #579.

stdlib/2/weakref.pyi

@@ -0,0 +1,47 @@
+# Stubs for weakref (Python 2)
+#
+# Based on stub automatically generated by stubgen.
+
+from typing import Any, MutableMapping, Generic, Iterator, List, TypeVar
+from _weakref import (getweakrefcount, getweakrefs, ref, proxy,
+                      CallableProxyType, ProxyType, ReferenceType)
+from _weakrefset import WeakSet
+
+ProxyTypes = ... # type: Any
+
+_KT = TypeVar('_KT')
+_VT = TypeVar('_VT')
+
+# Don't inherit from typing.Dict since
+# isinstance(weakref.WeakValueDictionary(), dict) is False
+class WeakValueDictionary(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
+    def itervaluerefs(self) -> Iterator[ReferenceType[_VT]]: ...
+    def valuerefs(self) -> List[ReferenceType[_VT]]: ...
+
+    def __setitem__(self, k: _KT, v: _VT) -> None: ...
+    def __delitem__(self, v: _KT) -> None: ...
+    def __getitem__(self, k: _KT) -> _VT: ...
+    def __len__(self) -> int: ...
+    def __iter__(self) -> Iterator[_KT]: ...
+
+    def has_key(self, key: _KT) -> bool: ...
+    def copy(self) -> WeakValueDictionary[_KT, _VT]: ...
+
+class WeakKeyDictionary(MutableMapping[_KT, _VT], Generic[_KT, _VT]):
+    def iterkeyrefs(self) -> Iterator[ReferenceType[_KT]]: ...
+    def keyrefs(self) -> List[ReferenceType[_KT]]: ...
+
+    def __setitem__(self, k: _KT, v: _VT) -> None: ...
+    def __delitem__(self, v: _KT) -> None: ...
+    def __getitem__(self, k: _KT) -> _VT: ...
+    def __len__(self) -> int: ...
+    def __iter__(self) -> Iterator[_KT]: ...
+
+    def has_key(self, key: _KT) -> bool: ...
+    def copy(self) -> WeakKeyDictionary[_KT, _VT]: ...
+
+# TODO: make generic
+class KeyedRef(ReferenceType):
+    key = ... # type: Any
+    def __new__(type, ob, callback, key): ...
+    def __init__(self, ob, callback, key): ...