$set = DateTime::Set->from_recurrence( 
        after => $start, 
        before => $end,
        recurrence => sub {
        return $_[0]->truncate( to => 'day' )->add( hours => 1 ) 
        }, 
    );
my $iter = $set->iterator;
while ( my $dt = $iter->next ) 
{
        print $dt->ymd;
};