A native library for GDExtension. The [GDExtension] resource type represents a [url=https://en.wikipedia.org/wiki/Shared_library]shared library[/url] which can expand the functionality of the engine. The [GDExtensionManager] singleton is responsible for loading, reloading, and unloading [GDExtension] resources. [b]Note:[/b] GDExtension itself is not a scripting language and has no relation to [GDScript] resources. $DOCS_URL/tutorials/scripting/gdextension/what_is_gdextension.html $DOCS_URL/tutorials/scripting/gdextension/gdextension_cpp_example.html Returns the lowest level required for this extension to be properly initialized (see the [enum InitializationLevel] enum). Returns [code]true[/code] if this extension's library has been opened. The library is initialized at the same time as the core features of the engine. The library is initialized at the same time as the engine's servers (such as [RenderingServer] or [PhysicsServer3D]). The library is initialized at the same time as the engine's scene-related classes. The library is initialized at the same time as the engine's editor classes. Only happens when loading the GDExtension in the editor.