How to group slices of strings

vvvv beta question
1

I have a spread of strings. Every string is an individual slice in my spread. I would like to group these slices into slices of 12.

for example:

0|a
1|b
2|c
3|d
4|e
5|f

to

0|abc
1|def

what is the best method to achieve this?

thanks

2

if that’s strings, use a + (String Spectral)