anchor.diff:    {ok, "1234"} = runcmd(E, "p"),
     {ok, ["asdf", "1234"]} = runcmd(E, ",p"),
   
  +  {ok, "asdf"} = runcmd(E, "-"),
  +  {ok, "1234"} = runcmd(E, "+"),
  +
     {ok, "asdf"} = runcmd(E, "1"),
  +  {ok, ""} = runcmd(E, "d"),
  +
  +  {ok, "1234"} = runcmd(E, "p"),
  +  {ok, ["1234"]} = runcmd(E, ",p"),
  +
  +  {ok, ""} = runcmd(E, "d"),
   
     ok.
   
  
positive.code:     ",p" -> {ok, sendRecv(E, list)};
      "p" -> {ok, sendRecv(E, print)};
      "d" -> sendRecv(E, delete), {ok, ""};
      _ -> Num = getnum(L),
           NumValid = numValid(E, Num),
           if NumValid -> sendRecv(E, setLineNumber, Num);
              true -> {error, unknown()}
           end
    end.
  
negative.code: test() ->
    E = start(),
    %[] = sendRecv(E, list),
    {ok, ""} = runcmd(E, ",p"),
  
    %{ok, ["asdf"]} = runcmd(E, "a"),
    %would need to handle input programmatically, maybe mode in runcmd or use an iobuffer
    %use sendRecv instead
    ok = sendRecv(E, append, "asdf"),
    {ok, "asdf"} = runcmd(E, "p"),
    {ok, ["asdf"]} = runcmd(E, ",p"),
  