python nested list comprehension string concatenation

Question

I have a list of lists in python looking like this:

[['a', 'b'], ['c', 'd']]

I want to come up with a string like this:

a,b;c,d

So the lists should be separated with a ; and the values of the same list should be separated with a ,

So far I tried ','.join([y for x in test for y in x]) which returns a,b,c,d. Not quite there, yet, as you can see.

Answer 1

";".join([','.join(x) for x in a])

Answer 2

>>> ';'.join(','.join(x) for x in [['a', 'b'], ['c', 'd']])
'a,b;c,d'