$ perl -MData::Dumper -we 'sub t{ $_+=1 for @_; print Dumper \@_;}  my %h = (1 => 2, 3 => 4); t(%h); print Dumper \%h'
$VAR1 = [
          2,
          3,
          4,
          5
        ];
$VAR1 = {
          '1' => 3,
          '3' => 5
        };