my $self = bless {}, $class;

    # Use an indexed hash to preserve the order.
    tie %{ $self->{sections} }, 'Tie::IxHash';

##</code><code>##

    tie %{undef}, 'Tie::IxHash';

##</code><code>##

    tie %{ $self->{sections}= {} }, 'Tie::IxHash';