# code: http://golf.shinh.org/reveal.rb?sort+by+first+occurrence/tails_1642141392&nbb
# target Nibbles version: 0.25
# commenter version: 0.1.2.181

+ #(concat):[chr] 
    =~ #(group by (also sorts)):[[chr]] 
        ;;@ #(= sndLine):[chr] 
        ~ #(nosort):null 
        #(implicit arg = A):chr <--arg( A:chr )