deep flatten python

1def spread(arg):
2    ret = []
3    for i in arg:
4        if isinstance(i, list):
5            ret.extend(i)
6        else:
7            ret.append(i)
8    return ret
9
10
11def deep_flatten(lst):
12    result = []
13    result.extend(
14        spread(list(map(lambda x: deep_flatten(x) if type(x) == list else x, lst))))
15    return result
16
17
18deep_flatten([1, [2], [[3], 4], 5]) # [1,2,3,4,5]