flatten.py

#!/usr/bin/env python3
from collections.abc import Iterable

data = [1,2,[3,4,[5,6,[7,8,[9,10,[[[11],12],[13,14,15]]]]]]]

def flatten(data):
    for value in data:
        if isinstance(value, (Iterable,)):
            # Call recursively to yield nested values from
            yield from flatten(value)
        else:
            # Any other type yields its value
            yield value

for value in flatten(data):
    print(value)