[[i for i in a] for a in data]

This is a nested list comprehension that creates a new list of lists. Each inner list contains the individual elements of the corresponding input list in the same order.

Here's how it works step by step:

1. The outer loop iterates over each list in `data`.
2. For each list `a` in `data`, the inner loop iterates over each element `i` in `a`.
3. The expression `i for i in a` creates a new list containing all the elements in `a`.
4. The entire expression `[i for i in a]` is evaluated for each `a` in `data`, resulting in a list of lists.
5. The final result is a new list that contains all the individual elements in `data`, arranged in the same order as the original lists.

For example, if `data` is `[[1, 2], [3, 4, 5], [6, 7]]`, the output will be `[[1, 2], [3, 4, 5], [6, 7]]` because each inner list in `data` is already a list of individual elements. If `data` is `[['a', 'b', 'c'], ['d'], ['e', 'f']]`, the output will be `[['a', 'b', 'c'], ['d'], ['e', 'f']]` because each inner list contains individual elements that are already arranged in the correct order.