code: function link(nextEntry, prevEntry) {
          if (nextEntry !== prevEntry) {
            if (nextEntry) nextEntry.p = prevEntry; //p stands for previous, 'prev' didn't minify
            if (prevEntry) prevEntry.n = nextEntry; //n stands for next, 'next' didn't minify
          }
        }
docs: bidirectionally links two entries of the LRU linked list