#!perl -l
use strict;
use warnings;

my $a = {child1 => [ {child2 => [ {child3 => [ {child4 => [1]} ]} ]} ]};
print $a->{child1}{child2}{child3}; #cut off {child3} and no problem.

print '$a:',ref $a;
print '$a->{child1}:',ref $a->{child1};
print '$a->{child1}{child2}:',ref $a->{child1}{child2};
print '@{$a->{child1}}:',scalar @{$a->{child1}};
__END__
$a:HASH
$a->{child1}:ARRAY
$a->{child1}{child2}:HASH
@{$a->{child1}}:28004977