Enhance Autocompletion for mobject.animate. to Display Mobject Methods (#2342)

* Improve autocompletion for mobject.animate to show Mobject methods

- Added type hint `-> _AnimationBuilder | Self` to `Mobject.animate`, enabling autocompletion for `Mobject` methods after `mobject.animate`.

- Prioritized `typing_extensions.Self` over `typing.Self` in imports, so autocompletion of `Mobject` methods also works in Python < 3.11.

* Support `mobject.animate.` autocompletion in IPython

* Add docstring to `__dir__` and add return type hint

* improve docsting `__dir__` _AnimationBuilder

manimlib/mobject/mobject.py

@@ -160,7 +160,7 @@ class Mobject(object):
         return self
 
     @property
-    def animate(self) -> _AnimationBuilder:
+    def animate(self) -> _AnimationBuilder | Self:
         """
         Methods called with Mobject.animate.method() can be passed
         into a Scene.play call, as if you were calling
@@ -2256,6 +2256,18 @@ class _AnimationBuilder:
     def __call__(self, **kwargs):
         return self.set_anim_args(**kwargs)
 
+    def __dir__(self) -> list[str]:
+        """
+        Extend attribute list of _AnimationBuilder object to include mobject attributes
+        for better autocompletion in the IPython terminal when using interactive mode.
+        """
+        methods = super().__dir__()
+        mobject_methods = [
+            attr for attr in dir(self.mobject)
+            if not attr.startswith('_')
+        ]
+        return sorted(set(methods+mobject_methods))
+
     def set_anim_args(self, **kwargs):
         '''
         You can change the args of :class:`~manimlib.animation.transform.Transform`, such as

manimlib/typing.py

@@ -7,9 +7,9 @@ if TYPE_CHECKING:
     import re
 
     try:
-        from typing import Self
-    except ImportError:
         from typing_extensions import Self
+    except ImportError:
+        from typing import Self
 
     # Abbreviations for a common types
     ManimColor = Union[str, Color, None]