Ah. It takes the translation as left argument and the iterable as right one. The translation has to be a pair of arrays, one for from, one for to. For example
[1,2],[3,4] y 1,2,3,4,5,6,1,2
(whitespace only for clarity) gives
[3, 4, 3, 4, 5, 6, 3, 4]
. (
link)