sub exec_data {
    my ($data, $level) = @_;
    print "id: $data->{id}\n";
    print "level: $level\n";
    if (exists $data->{data}) {
        exec_data($_, $level +1) for @{$data->{data}};
    }
}

exec_data($_, 1) for @{$data->{data}};