How to use the csso.clone function in csso

if (selectedEl.hasAttr('style')) {
        elInlineStyleAttr = selectedEl.attr('style');
        elInlineStyles = elInlineStyleAttr.value;
      }
      var inlineCssAst = csso.parse(elInlineStyles, { context: 'block' });

      // merge element(inline) styles + matching <style> styles
      var newInlineCssAst = csso.parse('', { context: 'block' }); // for an empty css ast (in block context)

      var mergedDeclarations = [];
      var _fetchDeclarations = function (node, item) {
        if (node.type === 'Declaration') {
          mergedDeclarations.push(item);
        }
      };
      var itemRulesetNodeCloned = csso.clone(selectorItem.rulesetNode);
      // clone to prevent leaking declaration references (csso.translate(...))
      csso.walk(itemRulesetNodeCloned, _fetchDeclarations);
      csso.walk(inlineCssAst, _fetchDeclarations);

      // sort by !important(ce)
      var mergedDeclarationsSorted = stable(mergedDeclarations, function (declarationA, declarationB) {
        var declarationAScore = ~~declarationA.data.value.important, // (cast boolean to number)
          declarationBScore = ~~declarationB.data.value.important; //  "
        return (declarationAScore - declarationBScore);
      });

      // to css
      for (var mergedDeclarationsSortedIndex in mergedDeclarationsSorted) {
        var declaration = mergedDeclarationsSorted[mergedDeclarationsSortedIndex];
        newInlineCssAst.declarations.insert(declaration);
      }</style>