how to use recursions to redce multiple lists to one code example

Example 1: flatten a list of list python

# idiomatic python

# using itertools
import itertools

list_of_list = [[1, 2, 3], [4, 5], [6]]
chain = itertools.chain(*images)

flattened_list = list(chain)
# [1, 2, 3, 4, 5, 6]

Example 2: flatten a list of lists python

flattened = [val for sublist in list_of_lists for val in sublist]