Quick Sort in Python

#quick sort
def partation(arr,start,end):
    pivot = arr[end]
    j = start - 1 # first time when start is 0 it will be -1

    for i  in range(start,end):
        if arr[i] < pivot:
            j += 1
            arr[i], arr[j] = arr[j], arr[i]

    j += 1
    arr[j], arr[end] = arr[end], arr[j]
    return j

def quickSort(arr, start, end):
    if start < end:
        partationIndex = partation(arr,start,end)
        quickSort(arr, start, partationIndex-1)
        quickSort(arr, partationIndex+1, end)

arr = [5,4,3,2,1]
print(arr)
quickSort(arr, 0, len(arr)-1)
print(arr)