How to get 2D array possible combinations

Question

I have the following 2D array:

String[M][]

String[0]
   \"1\",\"2\",\"3\"

String[1]
   \"A\", \"B\"
   .
   .
   .
String[M-1]
   \"!\"

A

Answer 1

In Python one uses itertools.product and argument unpacking (apply)

>>> import itertools
>>> S=[['1','2','3'],['A','B'],['!']]
>>> ["".join(x) for x in itertools.product(*S)]
['1A!', '1B!', '2A!', '2B!', '3A!', '3B!']