Its probably quite simple but I cant find it.
There is a tree (multiple lists, of which some lists are empty), I would like to add a number to all the numbers which are present. However when a list is empty it has to remain empty.
When I simply add 4 -> also the ‘empty’ list is ‘filled’ with 4.
Besides its important that the 3 lists/branch remain the same. (this is why clean tree, before adding 4 won’t help)
Thank you in advance,