src/vs/workbench/browser/parts/editor/editorPart.ts/EditorPart/findGroup
class EditorPart:	findGroup(scope: IFindGroupScope, source: IEditorGroupView | GroupIdentifier = this.activeGroup, wrap?: boolean): IEditorGroupView | undefined {

		// by direction
		if (typeof scope.direction === 'number') {
			return this.doFindGroupByDirection(scope.direction, source, wrap);
		}

		// by location
		if (typeof scope.location === 'number') {
			return this.doFindGroupByLocation(scope.location, source, wrap);
		}

		throw new Error('invalid arguments');
	}