pretty print timestamps in erlang

gistfile1.erl

%% pretty print timestamp from lager/src/lager_utils.erl

localtime_ms() ->
    {_, _, Micro} = Now = os:timestamp(),
    {Date, {Hours, Minutes, Seconds}} = calendar:now_to_local_time(Now),
    {Date, {Hours, Minutes, Seconds, Micro div 1000 rem 1000}}.

format_time() ->
    format_time(localtime_ms()).

format_time({{Y, M, D}, {H, Mi, S, Ms}}) ->
    {io_lib:format("~b-~2..0b-~2..0b", [Y, M, D]),
        io_lib:format("~2..0b:~2..0b:~2..0b.~3..0b", [H, Mi, S, Ms])};
format_time({{Y, M, D}, {H, Mi, S}}) ->
    {io_lib:format("~b-~2..0b-~2..0b", [Y, M, D]),
        io_lib:format("~2..0b:~2..0b:~2..0b", [H, Mi, S])}.