anchor.diff:          updater=Updater,
           commit_delay=Delay
       } = State,
  +    assert_signature_match(Mod, OldIdxState, NewIdxState),
       NewSeq = Mod:get(update_seq, NewIdxState),
       OldSeq = Mod:get(update_seq, OldIdxState),
       % For indices that require swapping files, we have to make sure we're
  
positive.code:     {ToSend, Remaining} = lists:partition(Pred, Waiters),
      [gen_server:reply(From, {ok, IdxState}) || {From, _} <- ToSend],
      Remaining.
  
negative.code:             {noreply, NewState}
      end;
  handle_cast({new_state, NewIdxState}, State) ->
      #st{
          mod=Mod,
          idx_state=OldIdxState,
          commit_delay=Delay
      } = State,
      assert_signature_match(Mod, OldIdxState, NewIdxState),
      CurrSeq = Mod:get(update_seq, NewIdxState),
      Args = [
          Mod:get(db_name, NewIdxState),
  