code: function (elm) {
        return Options.liftN([
          CaretFinder.firstPositionIn(elm),
          CaretFinder.lastPositionIn(elm)
        ], function (firstPos, lastPos) {
          var normalizedFirstPos = InlineUtils.normalizePosition(true, firstPos);
          var normalizedLastPos = InlineUtils.normalizePosition(false, lastPos);
  
          return CaretFinder.nextPosition(elm, normalizedFirstPos).map(function (pos) {
            return pos.isEqual(normalizedLastPos);
          }).getOr(true);
        }).getOr(true);
      }
docs: Checks for delete at <code>|a</code> when there is only one item left except the zwsp caret container nodes