Method cursor

crates/stdlib/src/_sqlite3.rs:1022–1050

(
            zelf: PyRef<Self>,
            args: CursorArgs,
            vm: &VirtualMachine,
        )

        #[pymethod]
        fn cursor(
            zelf: PyRef<Self>,
            args: CursorArgs,
            vm: &VirtualMachine,
        ) -> PyResult<PyObjectRef> {
            zelf.db_lock(vm).map(drop)?;

            let factory = match args.factory {
                OptionalArg::Present(f) => f,
                OptionalArg::Missing => Cursor::class(&vm.ctx).to_owned().into(),
            };

            let cursor = factory.call((zelf.clone(),), vm)?;

            if !cursor.class().fast_issubclass(Cursor::class(&vm.ctx)) {
                return Err(vm.new_type_error(format!(
                    "factory must return a cursor, not {}",
                    cursor.class()
                )));
            }

            if let Some(cursor_ref) = cursor.downcast_ref::<Cursor>()
                && let Some(factory) = zelf.row_factory.to_owned()
            {
                let _ = unsafe { cursor_ref.row_factory.swap(Some(factory)) };
            }

            Ok(cursor)
        }

        #[pymethod]
        fn blobopen(