file_server
init(X1::[]) -> {ok, state()} | {stop, term()}
handle_call(Request::term(), From::term(), Handle::state()) -> {noreply, state()} | {reply, eof | ok | {error, term()} | {ok, term()}, state()} | {stop, normal, stopped, state()}
handle_cast(Msg::term(), State::state()) -> {noreply, state()}
handle_info(Info::term(), Handle::state()) -> {noreply, state()} | {stop, normal, state()}
terminate(Reason::term(), Handle::state()) -> ok
code_change(OldVsn::term(), State::state(), Extra::term()) -> {ok, state()}