pep-484: session, instancestate, etc

Also adds some fixes to annotation-based mapping
that have come up, as well as starts to add more
pep-484 test cases

Change-Id: Ia722bbbc7967a11b23b66c8084eb61df9d233fee

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/sqlalchemy/orm/state_changes.py b/lib/sqlalchemy/orm/state_changes.py
index 1afeab05b..b7bf96558 100644
--- a/lib/sqlalchemy/orm/state_changes.py
+++ b/lib/sqlalchemy/orm/state_changes.py
@@ -16,12 +16,15 @@ from typing import Any
 from typing import Callable
 from typing import Optional
 from typing import Tuple
+from typing import TypeVar
 from typing import Union
 
 from .. import exc as sa_exc
 from .. import util
 from ..util.typing import Literal
 
+_F = TypeVar("_F", bound=Callable[..., Any])
+
 
 class _StateChangeState(Enum):
     pass
@@ -60,7 +63,7 @@ class _StateChange:
             Literal[_StateChangeStates.ANY], Tuple[_StateChangeState, ...]
         ],
         moves_to: _StateChangeState,
-    ) -> Callable[..., Any]:
+    ) -> Callable[[_F], _F]:
         """Method decorator declaring valid states.
 
         :param prerequisite_states: sequence of acceptable prerequisite