What is the complexity of the sorted() function?

Question

I have a list of lists and I am sorting them using the following

data=sorted(data, key=itemgetter(0))

Was wondering what is the runtime complexity of this python function?

Answer 1

Provided itemgetter(0) is O(1) when used with data, the sort is O(n log n) both on average and in the worst case.

For more information on the sorting method used in Python, see Wikipedia.