my $writer = $respond->(200, 
        [ 'Content-Disposition' => 'attachment; filename="data.csv"' ] );

##</code><code>##

    my $writer = $respond->([200, 
        [ 'Content-Disposition' => 'attachment; filename="data.csv"' ]] );

##</code><code>##

    my $writer = $respond->([200, 
        ['Content-Type' => 'text']] );