$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my %hash = (
>    011 => q{nine},
>    11  => q{eleven},
>    _2t => q{fruity},
>    );
> print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );'
%hash = (
          '11' => 'eleven',
          '_2t' => 'fruity',
          '9' => 'nine'
        );
$
$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my %hash = (
>    08  => q{eight},
>    11  => q{eleven},
>    _2t => q{fruity},
>    );
> print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );'
Illegal octal digit '8' at -e line 3, at end of line
Execution of -e aborted due to compilation errors.
$