When we animate from a use, we should not consider its matrix because the matrix of the destination group is apply to the whole <svg:use> include its matrix. Seperate scale tween into three functions to reduce its size.

divert([-1])

define([_arg1], [$1])

define([_foreach], [ifelse([$2], [()], [],
[define([$1], _arg1$2)$3[]_foreach([$1], (shift$2), [$3])])])

define([foreach], [pushdef([$1])_foreach($@)popdef([$1])])

divert[]dnl