my $href = {
  'x' => {
     'y' => {
         'z' => [ $xref, $yref, $zref ],
      },
     'strange' => { ..... },
  },
  'charm' => { .... },
};

##</code><code>##

foreach  my $obj  (%{$href})
# This dereference ^ causes a deep copy to be made

##</code><code>##

01: my $list = [1, 2, 3];
02: doStuff($list);
03: 
04: sub doStuff
05: {
06:   my $listRef = shift;
07:   foreach $listElement (@{$listRef})
08:   {
09:     print "$listElement \n";
10:   }
11: }