code: function (collection, elements, settings, index) {
              for (var i = index + 1; i < elements.length; i++) {
                  elements = swapElements(collection, elements, i - 1, i);
              }
              return collection.find(settings.elements_selector);
          }
docs: if we create an element at position 2, all element indexes from 2 to N should be increased. for example, in 0-A 1-B 2-C 3-D, adding X at position 1 will create 0-A 1-X 2-B 3-C 4-D