code: function () {
                  if (agent.isW3CRangeSupport) {
                      var w3cRange = document.createRange();
                      w3cRange.setStart(sc, so);
                      w3cRange.setEnd(ec, eo);
  
                      return w3cRange;
                  } else {
                      var textRange = pointToTextRange({
                          node: sc,
                          offset: so
                      });
  
                      textRange.setEndPoint('EndToEnd', pointToTextRange({
                          node: ec,
                          offset: eo
                      }));
  
                      return textRange;
                  }
              }
docs: nativeRange: get nativeRange from sc, so, ec, eo