anchor.diff:              materialize(Type, Snapshot, SnapshotCommitTime, SnapshotTime, Rest, TxId, LastOpCommitTime)
       end.
   
  -%% @doc Check whether an udpate is included in a snapshot and also
  -%%		if that update is newer than a snapshot's commit time
  -%%      Input: Dc = Datacenter Id
  -%%             CommitTime = local commit time of this update at DC
  -%%             SnapshotTime = Orddict of [{Dc, Ts}]
  -%%			   SnapshotCommitTime = commit time of that snapshot.
  -%%      Outptut: true or false
  --spec is_op_in_snapshot(commit_time(), snapshot_time(), commit_time() | ignore) -> 
  -  boolean().
  +%% @doc Checks whether a commit time is included in a snapshot time and, if not ignored,
  +%%		whether the commit time is more recent than some commit time.
  +-spec is_op_in_snapshot(commit_time(), snapshot_time(), commit_time() | ignore) -> boolean().
   is_op_in_snapshot(OperationCommitTime, SnapshotTime, SnapshotCommitTime) ->
  -	{OpDc, OpCommitTime}= OperationCommitTime,
  +	{OpDc, OpCommitTime} = OperationCommitTime,
       {ok, Ts} = vectorclock:get_clock_of_dc(OpDc, SnapshotTime),
       case SnapshotCommitTime of
       ignore -> 
  
positive.code:                                 vectorclock:from_list([{1,1}]),
                                  Ops, ignore, ignore),
      ?assertEqual(0,crdt_pncounter:value(PNCounter2)).
      
      
      
      
  is_op_in_snapshot_test()->
  	OpCT1 = {dc1, 1},
  	ST1 = vectorclock:from_list([{dc1, 2}]),
  	ST2 = vectorclock:from_list([{dc1, 0}]),
  	true = is_op_in_snapshot(OpCT1, ST1, ignore),
  	false = is_op_in_snapshot(OpCT1, ST2, ignore).
      
      
  -endif.
  
negative.code:     Op4 = #clocksi_payload{key = abc, type = crdt_pncounter,
                             op_param = {update,{{increment,2},1}},
                             commit_time = {1, 4}, txid = 4},
      Ops = [Op1, Op2, Op3, Op4],
  
      {ok, PNCounter2, CommitTime2} = materialize(crdt_pncounter,
                                        PNCounter, ignore, vectorclock:from_list([{1,3}]),
                                        Ops, ignore),
  