I have a list of multiple list-of-lists in python:

```
a = [[[0,1,2], [10,11,12]],
     [[3,4,5], [13,14,15]]]

```

And I would like to merge all the first lists together, the second lists together, and so forth:

```
final = [[0,1,2,3,4,5],
         [10,11,12,13,14,15]]

```

The furthest I've got is to try to unzip the outer lists:

```
zip(*a) = [([0,1,2], [3,4,5]), 
           ([10,11,12], [13,14,15])]

```

I suppose one could loop through these and then chain each together, but that seems wasteful. What's a pythonic way to fix this?

**NOTE**: 
There might be more than two sublists in each "row".