def test_collapse_with_nested_collection(self):
    c = Collection([Collection([1, 2, 3]), Collection([4, 5, 6])])
    self.assertEqual([1, 2, 3, 4, 5, 6], c.collapse().all())
def test_collapse_with_nested_collection(self):
    c = Collection([Collection([1, 2, 3]), Collection([4, 5, 6])])
    self.assertEqual([1, 2, 3, 4, 5, 6], c.collapse().all())