Take the content of a list and append it to another list

Question

I am trying to understand if it makes sense to take the content of a list and append it to another list.

I have the first list created through a loop function, that

Answer 1

Using the map() and reduce() built-in functions

def file_to_list(file):
     #stuff to parse file to a list
     return list

files = [...list of files...]

L = map(file_to_list, files)

flat_L = reduce(lambda x,y:x+y, L)

Minimal "for looping" and elegant coding pattern :)