\l tck/factor

each:D[(`jump;(`r;`uncons;`r_;`tuck;`r;`r;`call;`r_;`r_;`each);,`drop2;`ifte)]

/ E(10 20 30;,(-:);`each)

tree_each:D[(`jump;(`jump;`list;(`r;`uncons;`r_;`tuck;,`tree_each;`dip2;`tree_each);,`call;`ifte);,`drop2;`ifte)]

/ E((1;2;3 4;5);,(-:);`tree_each)