# every Monday, from 10:00 to 15:00
my $start = DateTime::Event::ICal->recur(
    freq   => 'weekly',
    byday  => ['mo'],
    byhour => 10
);
my $end = DateTime::Event::ICal->recur(
    freq   => 'weekly',
    byday  => ['mo'],
    byhour => 15
);
my $set = DateTime::SpanSet->from_sets(
    start_set => $start,
    end_set   => $end
);

print "Format for storage ",
 DateTime::Format::ICal->format_recurrence( $set );

##</code><code>##

format_recurrence() - Format not implemented for this unbounded set