Do not use True or False as default values in assignments (#7060)

stdlib/@python2/typing.pyi

@@ -37,7 +37,7 @@ _F = TypeVar("_F", bound=Callable[..., Any])
 def final(f: _F) -> _F: ...
 def overload(f: _F) -> _F: ...
 
-Literal: _SpecialForm
+Literal: _SpecialForm = ...
 # TypedDict is a (non-subscriptable) special form.
 TypedDict: object
 
@@ -304,7 +304,7 @@ class MutableMapping(Mapping[_KT, _VT], Generic[_KT, _VT]):
 
 Text = unicode
 
-TYPE_CHECKING = True
+TYPE_CHECKING: Literal[True]
 
 class IO(Iterator[AnyStr], Generic[AnyStr]):
     # TODO detach

stdlib/typing.pyi

@@ -502,7 +502,7 @@ class MutableMapping(Mapping[_KT, _VT], Generic[_KT, _VT]):
 
 Text = str
 
-TYPE_CHECKING = True
+TYPE_CHECKING: _Literal[True]
 
 # In stubs, the arguments of the IO class are marked as positional-only.
 # This differs from runtime, but better reflects the fact that in reality

stubs/python-gflags/gflags.pyi

@@ -100,11 +100,11 @@ class Flag:
     value: Any
     help: str
     short_name: str
-    boolean = False
-    present = False
+    boolean: bool
+    present: bool
     parser: ArgumentParser
     serializer: ArgumentSerializer
-    allow_override = False
+    allow_override: bool
     def __init__(
         self,
         parser: ArgumentParser,