anchor.diff:  %% ----- SNAPSHOT INTERFACE ------------------------------------------------
   
   % backup existing snapshot
  +-spec(
  +    zip(all | {re, string()} | {files, [string()]}) ->
  +        ok | string()
  +).
   zip(all) -> zip({re, "*"++?BKP_EXTN});
   zip({re, MatchPattern}) ->
       {_, SnapDir} = application:get_env(imem, imem_snapshot_dir),
  
positive.code:             Error
      end.
  
  restore(zip, ZipFile, TabRegEx, Strategy, Simulate) when is_list(ZipFile) ->
      case filelib:is_file(ZipFile) of
          true ->
  
negative.code:             file:del_dir(Path)
      end.
  
  -spec(
      do_snapshot(function()) ->
          ok | term() | {error, {string(), term()}}
  ).
  do_snapshot(SnapFun) ->
      try
          ok = case SnapFun of
  