code: Map.Entry<Integer, Map.Entry> getNearestAnchorEntry() {
          int anchorCount = anchorList.size();
          if (page == 0 || anchorCount == 0) {
              return NULL_ANCHOR;
          }
  
          Map.Entry anchoredEntry;
          if (page < anchorCount) {
              anchoredEntry = anchorList.get(page - 1);
          } else {
              anchoredEntry = anchorList.get(anchorCount - 1);
          }
          return anchoredEntry;
      }
docs: After each query, an anchor entry is set for that page. see {@link #setAnchor(int, Map.Entry)}}
  For the next query user may set an arbitrary page. see {@link #setPage(int)}
  for example: user queried first 5 pages which means first 5 anchor is available
  if the next query is for the 10th page then the nearest anchor belongs to page 5
  but if the next query is for the 3nd page then the nearest anchor belongs to page 2
  
  @return nearest anchored entry for current page