@Nullable
  public ThreeSide getEditorSide(@Nullable Editor editor) {
    if (getEditor(ThreeSide.BASE) == editor) return ThreeSide.BASE;
    if (getEditor(ThreeSide.RIGHT) == editor) return ThreeSide.RIGHT;
    if (getEditor(ThreeSide.LEFT) == editor) return ThreeSide.LEFT;
    return null;
  }
@Nullable
  public ThreeSide getEditorSide(@Nullable Editor editor)