sub get {
    my( $self, @pos ) = @_;

    #return @{ $self->{'a'} }[ @pos ];
    return @{ $self->{'a'} }[ map $_-1, @pos ];
}

sub set {
    my( $self, %lines ) = @_;

    my @pos = keys %lines;

    #@{ $self->{'a'} }[ @pos ] = @lines{ @pos };
    @{ $self->{'a'} }[ map $_-1, @pos ] = @lines{ @pos };

    return $self;
}