docs: function removeHighlight() {
          for (var h in selection._highlighter) {
            var highlighter = selection._highlighter[h];
  
            var parent = highlighter.parentNode;
            while (highlighter.firstChild) {
              parent.insertBefore(highlighter.firstChild, highlighter);
            }
            parent.removeChild(highlighter);
          }
  
          selection._highlighter = undefined;
        }