Python 2.7 : How to edit List with respect to index

dataList = ['Adam','Jack','Subu','Mark']
# get index in list
itemIndex = dataList.index('Jack')
print 'Position in list: ',itemIndex

# replace Jack with Tom
dataList[itemIndex] = 'Tom'
print 'Updated list: ', dataList

Position in list:  1

Updated list:  ['Adam', 'Tom', 'Subu', 'Mark']