anchor.diff:  -type n_val() :: non_neg_integer().
   -type ring() :: term().
   -type preflist() :: [{index(), node()}].
  +-type preflist2() :: [{{index(), node()}, primary|fallback}].
   
   %% Return preflist of all active primary nodes (with no
   %% substituion of fallbacks).  Used to simulate a
  
positive.code: check_up([{Partition,Node}|Rest], UpNodes, Up, Pangs) ->
      case is_up(Node, UpNodes) of
          true ->
              check_up(Rest, UpNodes, [{Partition, Node} | Up], Pangs);
          false ->
              check_up(Rest, UpNodes, Up, [{Partition, Node} | Pangs])
      end.
  
negative.code: %% -------------------------------------------------------------------
  -module(riak_core_apl).
  -export([active_owners/1, active_owners/2,
           get_apl/3, get_apl/4, get_apl2/4,
           get_primary_apl/3, get_primary_apl/4
          ]).
  
  