code: function updateNewIndicesAfterSlot(slot, indexDelta) {
                      // Adjust all the indexNews after this slot
                      for (slot = slot.next; slot; slot = slot.next) {
                          if (slot.firstInSequence) {
                              var indexNew = (slot.indexNew !== undefined ? slot.indexNew : slot.index);
                              if (indexNew !== undefined) {
                                  slot.indexNew = indexNew + indexDelta;
                              }
                          }
                      }
  
                      // Adjust the overall count
                      countDelta += indexDelta;
  
                      indexUpdateDeferred = true;
  
                      // Increment currentRefreshID so any outstanding fetches don't cause trouble.  If a refresh is in progress,
                      // restart it (which will also increment currentRefreshID).
                      if (refreshInProgress) {
                          beginRefresh();
                      } else {
                          currentRefreshID++;
                      }
                  }
docs: Updates the new index of the first slot in each sequence after the given slot