Some refactor

Author: yauhenipakala

src/highlightjs-line-numbers.js

@@ -63,33 +63,26 @@
     function lineNumbersBlock (element, options) {
         if (typeof element !== 'object') return;
 
-        // define options or set default
-        options = options || {
-            singleLine: false
-        };
-
-        // convert options
-        var firstLineIndex = !!options.singleLine ? 0 : 1;
-
         async(function () {
-
-            duplicateMultilineNodes(element);
-
-            element.innerHTML = addLineNumbersBlockFor(element.innerHTML, firstLineIndex);
+            element.innerHTML = lineNumbersInternal(element, options);
         });
     }
 
     function lineNumbersValue (value, options) {
         if (typeof value !== 'string') return;
 
+        var element = document.createElement('code')
+        element.innerHTML = value
+
+        return lineNumbersInternal(element, options);
+    }
+
+    function lineNumbersInternal (element, options) {
         // define options or set default
         options = options || {
             singleLine: false
         };
 
-        var element = document.createElement('code')
-        element.innerHTML = value
-
         // convert options
         var firstLineIndex = !!options.singleLine ? 0 : 1;