anchor.diff:  delete(Cache2, N, X, APageId, A = #page{p0 = AP0, e = AE}) ->
     ?dbg("delete(~p, ~p)~n", [X, A]),
     case binsearch(AE, X) of
  -    {not_found, R} ->
  +    ?not_found(R) ->
         QPageId =
           if R =:= 0 -> AP0;
              true -> item_p(element(R, AE))
  
positive.code: 
  search_page(IO, X, P = #page{p0 = P0, e = E}, Path) ->
    case binsearch(E, X) of
      {not_found, R} ->
        Q =
          if R =:= 0 -> P0;
             true -> item_p(element(R, E))
          end,
        search_pageid(IO, X, Q, [{P, R} | Path]);
      {found, K} ->
        {true, P, K, Path}
    end.
  
  
negative.code:   K = (L + R) div 2,
    KX = item_k(element(K, E)),
    if X < KX -> binsearch(E, X, L, K - 1);
       X =:= KX -> ?found(K);
       true -> binsearch(E, X, K + 1, R)
    end;
  binsearch(_E, _X, _L, R) ->
    ?not_found(R).
  
  %%%_* B-tree Search ============================================================
  %%%
  