docs: function(textRange) {
                  var parentEl = textRange.parentElement();
                  var range = textRange.duplicate();
                  range.collapse(true);
                  var startEl = range.parentElement();
                  range = textRange.duplicate();
                  range.collapse(false);
                  var endEl = range.parentElement();
                  var startEndContainer = (startEl == endEl) ? startEl : dom.getCommonAncestor(startEl, endEl);
  
                  return startEndContainer == parentEl ? startEndContainer : dom.getCommonAncestor(parentEl, startEndContainer);
              }