A provider that can contribute items to the status bar that appears below a cell's editor.
An optional event to signal that statusbar items have changed. The provide method will be called again.
The provider will be called when the cell scrolls into view, when its content, outputs, language, or metadata change, and when it changes execution state.
The cell for which to return items.
A token triggered if this request should be cancelled.
One or more cell statusbar items