(3,4,5) | (7,8,9)
=== ((3,4),5) | ((7,8),9)
=== (4,5) | ((7,8),9)
=== 5 | ((7,8),9)
=== 5 | (8,9)
=== 5 | 9
=== 13

##</code><code>##

my @list2 = @{ $c->bbox('all') || [ 1,2,3 ] };

##</code><code>##

my @list2 = $c->bbox('all');
@list2 = (1,2,3) if !@list2;