Merge Sort in Python

# Helper merge sort function
def mergeSort(arr):
   # Clone the array for the merge later
   arrClone = arr.clone()
   mergeSortAux(arr, arrClone, 0, len(arr) - 1)

# Actual merge sort 
def mergeSortAux(arr, arrClone, low, high):
   if low < high:
       mid = (low + high) / 2
       # Sort left
       mergeSortAux(arr, arrClone, low, mid)
       # Sort right
       mergeSortAux(arr, arrClone, mid + 1, high)
       # Merge
       merge(arr, arrClone, low, mid, high)

# Merge definition that sorts two sub arrays
def merge(arr, arrClone, low, mid, high):
   i = low
   j = mid + 1
   # Copy the clone array parts over
   for k in range(low, high):
       arrClone[k] = arr[k]

   for k in range(low, high):
       if i > mid:
           arr[k] = arrClone[j]
           j += 1
       elif j > high:
           arr[k] = arrClone[i]
           i += 1
       elif arrClone[i] > arrClone[j]:
           arr[k] = arrClone[j]
           j += 1
       else:
           arr[k] = arrClone[i]
           i += 1