Flatting nested lists using generators

flatten_list.py

# coding: utf-8
import unittest


def flat_list(input_list):
    def flatten(lst):
        for i in lst:
            if isinstance(i, list):
                for j in flatten(i):
                    yield j
            else:
                yield i

    return list(flatten(input_list))


class TestFlattingMethod(unittest.TestCase):
    def setUp(self):
        self.lists = [
            [
                [[1, 2, [3]], 4],
                [1, 2, 3, 4]
            ],
            [
                [[4, 6], [5, 5], [6, 7]],
                [4, 6, 5, 5, 6, 7],
            ],
            [
                [6, 3, [3], 12, [[[32], 43], 1], 0],
                [6, 3, 3, 12, 32, 43, 1, 0],
            ]
        ]

    def test_flatten_method(self):
        for lst in self.lists:
            self.assertEqual(flat_list(lst[0]), lst[1])
            print('OK: flat_list {} == {}'.format(lst[0], lst[1]))


if __name__ == '__main__':
    unittest.main()