Fix typing of FunctionOverride

Author: dandavison

manim/animation/animation.py

@@ -16,7 +16,7 @@
 
 
 from copy import deepcopy
-from typing import TYPE_CHECKING, Callable, Iterable, Sequence
+from typing import TYPE_CHECKING, Callable, Iterable, Self, Sequence, cast
 
 if TYPE_CHECKING:
     from manim.scene.scene import Scene
@@ -112,7 +112,7 @@ def __new__(
         *args,
         use_override=True,
         **kwargs,
-    ):
+    ) -> Self:
         if isinstance(mobject, Mobject) and use_override:
             func = mobject.animation_override_for(cls)
             if func is not None:
@@ -122,7 +122,7 @@ def __new__(
                     f"{type(mobject).__name__} mobjects. use_override = False can "
                     f" be used as keyword argument to prevent animation overriding.",
                 )
-                return anim
+                return cast(Self, anim)
         return super().__new__(cls)
 
     def __init__(

manim/typing.py

@@ -561,7 +561,7 @@
 # Due to current limitations
 # (see https://github.com/python/mypy/issues/14656 / 8263),
 # we don't specify the first argument type (Mobject).
-FunctionOverride: TypeAlias = Callable[..., None]
+FunctionOverride: TypeAlias = Callable
 """Function type returning an :class:`~.Animation` for the specified
 :class:`~.Mobject`.
 """