src/vs/platform/undoRedo/common/undoRedoService.ts/ResourceEditStack/toString
class ResourceEditStack:	public toString(): string {
		let result: string[] = [];
		result.push(`* ${this.strResource}:`);
		for (let i = 0; i < this._past.length; i++) {
			result.push(`   * [UNDO] ${this._past[i]}`);
		}
		for (let i = this._future.length - 1; i >= 0; i--) {
			result.push(`   * [REDO] ${this._future[i]}`);
		}
		return result.join('\n');
	}