anchor.diff:      ",p" -> {ok, sendRecv(E, list)};
       "p" -> {ok, sendRecv(E, print)};
       "d" -> sendRecv(E, delete), {ok, ""};
  +    "+" -> N = sendRecv(E, getLineNumber),
  +           sendRecv(E, setLineNumber, N + 1),
  +           {ok, sendRecv(E, print)};
  +    "-" -> N = sendRecv(E, getLineNumber),
  +           sendRecv(E, setLineNumber, N - 1),
  +           {ok, sendRecv(E, print)};
       _ -> Num = getnum(L),
            NumValid = numValid(E, Num),
  -         if NumValid -> sendRecv(E, setLineNumber, Num);
  +         if NumValid -> sendRecv(E, setLineNumber, Num),
  +                        {ok, sendRecv(E, print)};
               true -> {error, unknown()}
            end
     end.
  
positive.code:   {ok, "1234"} = runcmd(E, "p"),
    {ok, ["asdf", "1234"]} = runcmd(E, ",p"),
  
    {ok, "asdf"} = runcmd(E, "1"),
  
    ok.
  
  
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"),
  