sqlalchemy: add return types for known magic methods (#9290)

stubs/SQLAlchemy/sqlalchemy/sql/elements.pyi

@@ -33,7 +33,7 @@ class ClauseElement(roles.SQLRole, SupportsWrappingAnnotations, MemoizedHasCache
     def self_group(self, against: Any | None = ...): ...
     def compile(self, bind: Any | None = ..., dialect: Any | None = ..., **kw): ...
     def __invert__(self): ...
-    def __bool__(self) -> None: ...
+    def __bool__(self) -> bool: ...
     def __nonzero__(self) -> bool: ...
 
 class ColumnElement(
@@ -284,7 +284,7 @@ class BinaryExpression(ColumnElement[Any]):
     def __init__(
         self, left, right, operator, type_: Any | None = ..., negate: Any | None = ..., modifiers: Any | None = ...
     ) -> None: ...
-    def __bool__(self): ...
+    def __bool__(self) -> bool: ...
     def __nonzero__(self) -> bool: ...
     @property
     def is_comparison(self): ...

stubs/SQLAlchemy/sqlalchemy/util/_collections.pyi

@@ -134,14 +134,14 @@ class IdentitySet:
     def __ixor__(self, other): ...
     def copy(self): ...
     __copy__: Any
-    def __len__(self): ...
+    def __len__(self) -> int: ...
     def __iter__(self): ...
     def __hash__(self) -> int: ...
 
 class WeakSequence:
     def __init__(self, __elements=...) -> None: ...
     def append(self, item) -> None: ...
-    def __len__(self): ...
+    def __len__(self) -> int: ...
     def __iter__(self): ...
     def __getitem__(self, index): ...
 

stubs/SQLAlchemy/sqlalchemy/util/langhelpers.pyi

@@ -139,7 +139,7 @@ def ellipses_string(value, len_: int = ...): ...
 
 class _hash_limit_string(compat.text_type):
     def __new__(cls, value, num, args): ...
-    def __hash__(self): ...
+    def __hash__(self) -> int: ...
     def __eq__(self, other): ...
 
 def warn(msg, code: Any | None = ...) -> None: ...