gistfile1.perl

use feature qw(switch);
use List::MoreUtils qw(firstidx);
my @a = 11..20; 

given(1) {
    when(1) {
#        my $_;
        my $i = firstidx { $_ % 5 == 0 } @a;
        print "$i $a[$i]\n";
    }
}