#! perl -sw
use strict;
my %hash = ( 
    I  => 1 
    , II => { 
                A=> 3
              , B=> { 1=> 4, 2=> 5, 3=> 6 } 
              } 
    , III=> 2 
);

sub hprint{
    return "$_[1] => $_[0]\n" unless ref $_[0];
    print for map { hprint( $_[0]{$_}, "$_[1]/$_" ) } keys %{ $_[0] };
    ();
}

hprint \%hash, 'hash';
__END__
D:\Perl\test>test
hash/II/B/1 => 4
hash/II/B/2 => 5
hash/II/B/3 => 6
hash/II/A => 3
hash/I => 1
hash/III => 2
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