Adding data to a nested list in Python

Question

I have a nested list e.g.:

nlist = [
         [1, 2, 3], 
         [4, 5, 6], 
         [7, 8, 9],
        ]

Before I insert this list into

Answer 1

If you are looking to create a new list then this will work as well...

nlistnew = [[a]+row for row in nlist]

EDIT: Fixed code as per Felix Kling's comment. Thanks!