Serialization ... one attribute per line ...

I have a set of syntax trees that I would like to serialize with one attribute per line, like this: https://github.com/biblicalhumanities/greek-new-testament/blob/master/syntax-trees/nestle1904-lowfat/xml/18-philemon.xml The current serialization looks more like this: https://github.com/biblicalhumanities/greek-new-testament/blob/master/syntax-trees/nestle1904/xml/18-philemon.xml Is there a way to get there using just serialization parameters, or do I need to do something fancier? Jonathan