def summa(numbers):
    """
    Дается последовательность целых чисел.
    Посчитать сумму без sum, import, for, while, reduce.

    """
    if not numbers:
        return 0
    return numbers[0] + summa(numbers[1:])


if __name__ == '__main__':
    # autotests
    assert summa([4, 2, -43, 5, 6, 0]) == -26, "First"
    assert summa([]) == 0, "Empty"
    assert summa([0, 0, 0, 0, 0, 0, 6]) == 6, "Six"
    assert summa([-40]) == -40, "Single"
    # failing:
    # assert summa([10, 20]) == 40, "Failing"
    print('Looks good')