def addition(*args):
"""Adds any quantity of numbers"""
def _initial_value():
return None if not args else 0
return reduce(_execute, flatten(args), _initial_value())
def test_flatten_nested_lists():
assert flatten([[[1, 2, 3]], 1]) == [1, 2, 3, 1]
def test_flatten_a_flattened_list():
assert flatten([1, 2, 3, 4]) == [1, 2, 3, 4]
def test_flatten_list_and_number():
assert flatten([1, [2, 3, 4]]) == [1, 2, 3, 4]
def test_flatten_an_empty_list():
assert flatten([]) == []