core: introduce do_for_each()
core: introduce do_for_each()

Useful when composing iteration with async operations.

aruanruan/scylla,gwicke/scylla,wildinto/scylla,gwicke/scylla,tempbottle/seastar,aruanruan/scylla,anzihenry/seastar,respu/scylla,kangkot/scylla,dwdm/scylla,glommer/scylla,scylladb/scylla-seastar,bowlofstew/scylla,avikivity/seastar,avikivity/scylla,linearregression/seastar,asias/scylla,victorbriz/scylla,shyamalschandra/seastar,mixja/seastar,bowlofstew/seastar,linearregression/scylla,eklitzke/scylla,bowlofstew/seastar,aruanruan/scylla,eklitzke/scylla,syuu1228/seastar,asias/scylla,wildinto/seastar,xtao/seastar,acbellini/scylla,wildinto/seastar,kjniemi/seastar,xtao/seastar,joerg84/seastar,syuu1228/seastar,rluta/scylla,anzihenry/seastar,justintung/scylla,flashbuckets/seastar,eklitzke/scylla,koolhazz/seastar,kjniemi/seastar,stamhe/seastar,ducthangho/imdb,cloudius-systems/seastar,stamhe/scylla,joerg84/seastar,senseb/scylla,leejir/seastar,linearregression/scylla,tempbottle/seastar,norcimo5/seastar,slivne/seastar,acbellini/scylla,rluta/scylla,xtao/seastar,bowlofstew/seastar,tempbottle/scylla,syuu1228/seastar,chunshengster/seastar,rentongzhang/scylla,chunshengster/seastar,anzihenry/seastar,kangkot/scylla,phonkee/scylla,dreamsxin/seastar,raphaelsc/seastar,duarten/scylla,senseb/scylla,rentongzhang/scylla,tempbottle/scylla,wildinto/scylla,jonathanleang/seastar,koolhazz/seastar,respu/scylla,mixja/seastar,glommer/scylla,dreamsxin/seastar,shyamalschandra/seastar,tempbottle/seastar,acbellini/seastar,stamhe/scylla,norcimo5/seastar,kjniemi/scylla,dwdm/seastar,dwdm/scylla,capturePointer/scylla,shaunstanislaus/scylla,printedheart/seastar,duarten/scylla,scylladb/scylla-seastar,gwicke/scylla,avikivity/scylla,shaunstanislaus/scylla,victorbriz/scylla,shaunstanislaus/scylla,ducthangho/imdb,raphaelsc/scylla,kjniemi/scylla,avikivity/scylla,bowlofstew/scylla,scylladb/scylla,avikivity/seastar,sjperkins/seastar,avikivity/seastar,norcimo5/seastar,shyamalschandra/seastar,hongliangzhao/seastar,kangkot/scylla,hongliangzhao/seastar,capturePointer/scylla,leejir/seastar,tempbottle/scylla,linearregression/scylla,hongliangzhao/seastar,acbellini/seastar,sjperkins/seastar,justintung/scylla,jonathanleang/seastar,mixja/seastar,bzero/seastar,raphaelsc/scylla,stamhe/scylla,scylladb/scylla,duarten/scylla,scylladb/seastar,dreamsxin/seastar,chunshengster/seastar,phonkee/scylla,scylladb/scylla-seastar,acbellini/seastar,koolhazz/seastar,printedheart/seastar,bzero/seastar,scylladb/seastar,guiquanz/scylla,wildinto/seastar,raphaelsc/seastar,stamhe/seastar,justintung/scylla,acbellini/scylla,printedheart/seastar,linearregression/seastar,guiquanz/scylla,victorbriz/scylla,senseb/scylla,asias/scylla,glommer/scylla,wildinto/scylla,cloudius-systems/seastar,flashbuckets/seastar,rluta/scylla,capturePointer/scylla,slivne/seastar,sjperkins/seastar,dwdm/seastar,bzero/seastar,bowlofstew/scylla,dwdm/seastar,flashbuckets/seastar,kjniemi/scylla,phonkee/scylla,stamhe/seastar,guiquanz/scylla,respu/scylla,scylladb/scylla,raphaelsc/scylla,jonathanleang/seastar,joerg84/seastar,linearregression/seastar,rentongzhang/scylla,ducthangho/imdb,slivne/seastar,leejir/seastar,cloudius-systems/seastar,kjniemi/seastar,scylladb/seastar,raphaelsc/seastar,dwdm/scylla,scylladb/scylla