use warnings;
use strict;

my @aoa = (
    [qw(1 1 1 1)],
    [qw(2 2 2)],
    'a string',
    [qw(3 3 3 3 3 3 3)],
    {a => 1, b => 2},
);

my $index = 0;

for (@aoa){
    if (ref $_ eq 'ARRAY'){
        my $element_count = scalar @$_;
        print "elem $index has $element_count elements\n";
    }
    else {
        print "elem $index is not an array reference\n";
    }

    $index++;
}