$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my %hash = (
>    1  => q{one},
>    11 => q{eleven}
>    );
> print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );'
%hash = (
          '11' => 'eleven',
          '1' => 'one'
        );
$
$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my %hash = (
>    1  => q{one},
>    11 => q{eleven},
>    2t => q{fruity},
>    );
> print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );'
syntax error at -e line 5, near "2t"
Execution of -e aborted due to compilation errors.
$
$ perl -Mstrict -Mwarnings -MData::Dumper -E '
> my %hash = (
>    1   => q{one},
>    11  => q{eleven},
>    _2t => q{fruity},
>    );
> print Data::Dumper->Dumpxs( [ \ %hash ], [ qw{ *hash } ] );'
%hash = (
          '11' => 'eleven',
          '1' => 'one',
          '_2t' => 'fruity'
        );
$