def insertionSort(arr):
    for index in range(1, len(arr)):
        j = index
        while j > 0 and arr[j-1] > arr[j]:
            arr[j], arr[j-1] = arr[j-1], arr[j]
            j -= 1
    return arr

print(insertionSort([5, 4, 3, 2, 1]))