shell-sort implementation in python

shell_sort.py

def shell_sort(array):
    gap = len(array) // 2
    while gap > 0:
        for i in range(gap, len(array)):
            for j in range(i - gap, -1, -1):
                if array[j] <= array[j + gap]:
                    break
                tmp = array[j]
                array[j] = array[j + gap]
                array[j + gap] = tmp
        gap //= 2
    return array