anchor.diff:              ?GET_CONFIG(snapshotClusterHourOfDay, [], 14,
                           "Hour of (00..23)day in which important tables must be snapshotted.")).
   
  +-spec(
  +    start_snap_loop() -> ok | pid()
  +).
  +-spec(
  +    restart_snap_loop() -> ok | term()
  +).
   -ifdef(TEST).
       start_snap_loop() -> ok.
       restart_snap_loop() -> ok.
  
positive.code: %% ----- SNAPSHOT INTERFACE ------------------------------------------------
  
  % backup existing snapshot
  zip(all) -> zip({re, "*"++?BKP_EXTN});
  zip({re, MatchPattern}) ->
      {_, SnapDir} = application:get_env(imem, imem_snapshot_dir),
  
negative.code:             {error, Error}
      end.
  
  -spec(
      timestamp({integer(), integer(), integer()}) -> integer()
  ).
  timestamp({Mega, Secs, Micro}) -> Mega*1000000000000 + Secs*1000000 + Micro.
  
  -spec(
      del_dirtree(file:name_all()) ->
          ok | {error, term()}
  ).
  del_dirtree(Path) ->
      case filelib:is_regular(Path) of
          true -> file:delete(Path);
  