def insertion_sort(array):
    """insertion_sort(list) -> list

    >>> insertion_sort([3, 2, 13, 4, 6, 5, 7, 8, 1, 20])
    [1, 2, 3, 4, 5, 6, 7, 8, 13, 20]
    """
    for index in range(1, len(array)):
        value_now = array[index]
        pos = index
        while pos > 0 and array[pos - 1] > value_now:
            array[pos] = array[pos - 1]
            pos = pos - 1
        array[pos] = value_now
    return array