anchor.diff:  %% It's up to the caller to ensure that the wait won't be forever.
   %% ===========================================================================
   
  +-spec wait(any())
  +   -> [{term(), pid()}].
  +
   wait(Pat) ->
       call({wait, Pat}).
   
  
positive.code:     call(uptime).
  
  %% pids/0
  %%
  %% Return: list of {Pid, [Term, ...]}
  
  pids() ->
      to_list(fun swap/1).
  
negative.code: id(T) -> T.
  
  %% terms/0
  
  -spec terms()
     -> [{term(), [pid()]}].
  
  terms() ->
      to_list(fun id/1).
  