Simple merge sort implementation

mergeSort.py

# Simple merge sort implementation
# reference: http://interactivepython.org/courselib/static/pythonds/SortSearch/TheMergeSort.html
import random


def mergeSort(iList):
    if len(iList) > 1:
        mid = len(iList) // 2
        lList = iList[:mid]
        rList = iList[mid:]

        mergeSort(lList)
        mergeSort(rList)

        l = 0
        r = 0
        i = 0
        while l < len(lList) and r < len(rList):
            if lList[l] < rList[r]:
                iList[i] = lList[l]
                l += 1
            else:
                iList[i] = rList[r]
                r += 1
            i += 1

        while l < len(lList):
            iList[i] = lList[l]
            l += 1
            i += 1

        while r < len(rList):
            iList[i] = rList[r]
            r += 1
            i += 1
    return iList


#   Testing
testList = random.sample(range(1, 100), 5)
print(testList)
print(mergeSort(testList))