For my understanding (ignoring the loop): between mark a and mark b: 'a,'b goto lines containing Abc: g/Abc recognizable substitute: s/yy/\=i/

For my understanding (ignoring the loop): between mark a and mark b: 'a,'b goto lines containing Abc: g/Abc recognizable substitute: s/yy/\=i/ = prefixes a variable (escaped with \) A problem is that it will only replace the first `yy` on the line (if you add g, to make it s/yy/\=i/g, it replaces all of them, but with the same value of i. How to make it increment multiple yy's on the one line?