Juggle with lists

flatten.py

def flatten(list_of_lists):
    if len(list_of_lists) == 0:
        return list_of_lists
    if isinstance(list_of_lists[0], list):
        return flatten(list_of_lists[0]) + flatten(list_of_lists[1:])
    return list_of_lists[:1] + flatten(list_of_lists[1:])


print(flatten([[1, 2, 3, 4], [5, 6, 7], [8, 9], [[10]]]))

# output
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]


print(flatten([[1,'a',['cat'],2],[[[3]],'dog'],4,5]))

# output
# [1, 'a', 'cat', 2, 3, 'dog', 4, 5]

flatten_v2.py

import itertools

# initializing the data
data = [[1, 2, 3], [4, 5], [6, 7, 8, 9, 10]]

# flattening the list and storing the result
flat_list = itertools.chain(*data)

# converting iterable to list and printing
print(list(flat_list))

# output
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

reverser.py

def mirrored(listtree):
    return [(mirrored(x) if isinstance(x, list) else x)
                             for x in reversed(listtree)]


print(mirrored([[1, 2], [3, 4], [5, 6, 7]]))

# output
# [[7, 6, 5], [4, 3], [2, 1]]