anchor.diff:    E = start(),
     cmdloop(E).
   
  +test() ->
  +  E = start(),
  +  [] = sendRecv(E, list),
  +  ok.
  +
  
positive.code:     "d" -> sendRecv(E, delete);
      _ -> Num = getnum(L),
           NumValid = numValid(E, Num),
           if NumValid ->
                sendRecv(E, setLineNumber, Num);
              true ->
                unknown()
           end
    end.
  
  
negative.code: % Ed tutorial: http://linuxclues.blogspot.com/2012/09/ed-tutorial-line-editor-unix.html
  
  -module(eed).
  -compile([debug_info, export_all]).
  
  fileed(Lines, Cursor) ->
  