Me Dev, You Jane

Just a quick one in the morning.

-module(knockknock).
-compile(export_all).

start_joke() ->
    register(person_1, erlang:spawn(knockknock, person1, [])),
    register(person_2, erlang:spawn(knockknock, person2, [])),
    person_1 ! start_joke.

relay(Person, Message) ->
    io:format("------- ~p -------~n", [Message]),
    Person ! Message.

person1() ->
    receive 
        start_joke ->
            relay(person_2, "Knock, Knock");
        "Who's There?" ->
            timer:sleep(100000),
            relay(person_2, "Java")
    end,
    person1().

person2() ->
    receive
        "Knock, Knock" ->
            relay(person_1, "Who's There?");
        "Java" ->
            relay(person_1, "Ha Ha")
    end,
    person2().