extract `ETAG_KINDS` to a constant
extract `ETAG_KINDS` to a constant

also use string interpolation instead of  addition

Wirachmat/sinatra,guidohcosta/sinatra,ksw2599/sinatra,eileencodes/sinatra,nju520/sinatra,sinatra/sinatra,midorineko/sinatra,d-bot/sinatra,burningTyger/sinatra,wzheng1/sinatra,DoraALin/sinatra,ktw1222/sinatra,mwpastore/sinatra,wzheng1/sinatra,mwpastore/sinatra,miyazawatomoka/sinatra,jkowens/sinatra,burningTyger/sinatra,howtolearntocode/sinatra,RosenDimov/sinatra,miyazawatomoka/sinatra,JonMidhir/sinatra,jkowens/sinatra,kumji/sinatra,d-bot/sinatra,porras/sinatra,eileencodes/sinatra,lastcat/sinatra,burningTyger/sinatra,davydovanton/sinatra,howtolearntocode/sinatra,nju520/sinatra,sethuster/sinatra,frechei/sinatra,jkowens/sinatra,nicoayala/sinatra,JonRowe/sinatra,kumji/sinatra,ganmacs/sinatra,DoraALin/sinatra,jenalgit/sinatra,Rayheng/sinatra,midorineko/sinatra,trexnix/sinatra,defsprite/sinatra,marocchino/sinatra,emiliocorpus/sinatra,autopp/sinatra,dariubs/sinatra,gferguson-gd/sinatra,ryanshaw/sinatra,ktw1222/sinatra,siberianbear/sinatra,lastcat/sinatra,JonRowe/sinatra,mwpastore/sinatra,ABaldwinHunter/sinatra-classic,emiliocorpus/sinatra,trexnix/sinatra,dariubs/sinatra,QLGu/sinatra,kyontan/sinatra,JonMidhir/sinatra,davydovanton/sinatra,guidohcosta/sinatra,laplaceliu/sinatra,sinatra/sinatra,Wirachmat/sinatra,JonMidhir/sinatra,frechei/sinatra,nicoayala/sinatra,defsprite/sinatra,siberianbear/sinatra,ABaldwinHunter/sinatra-classic,ksw2599/sinatra,autopp/sinatra,kgrz/sinatra,sethuster/sinatra,laplaceliu/sinatra,ganmacs/sinatra,kyontan/sinatra,Rayheng/sinatra,gferguson-gd/sinatra,cyberid41/sinatra,RosenDimov/sinatra,QLGu/sinatra,ryanshaw/sinatra,jenalgit/sinatra,cyberid41/sinatra,porras/sinatra