def insertion_sort(array):
    """ Insertion sort implementation

    Arguments:
        - array : (int[]) array of int to sort

    Returns:
        - array : (int[]) sorted numbers
    """
    for i in range(len(array)):
        j = i
        while j > 0 and array[j] < array[j-1]:
            array[j], array[j-1] = array[j-1], array[j]
            j -= 1
    return array