Add a simple protocol helper

src/geef_pkt.erl

@@ -0,0 +1,8 @@
+-module(geef_pkt).
+
+-export([line/1]).
+
+-spec line(iolist()) -> iolist().
+line(Text) ->
+    Prefix = io_lib:format("~4.16.0b", [iolist_size(Text) + 1]),
+    [Prefix, Text, "\n"].