A somewhat-undocumented feature of black is that in recent versions, by giving the list a trailing comma, you're telling the indenter to always put it on multip

A somewhat-undocumented feature of black is that in recent versions, by giving the list a trailing comma, you're telling the indenter to always put it on multiple lines (eg `[1,2,]` will always wrap on 4 lines). If you remove the trailing comma to a multi-item list/dict/whatever, black will try to compact the literal to a single line (and if it fails because the line is too long, it will add the trailing comma back)