unpacking lists inside another list python [duplicate]

Question

Assume you have a list :

mylist=[[1,2,3,4],[2,3,4,5],[3,4,5,6]]

any pythonic(2.x) way to unpack the inner lists so that new list should look like ?:

mylist_n=[1,2,3,4,2,3,4,5,3,4,5,6]

Answer 1

import itertools
mylist=[[1,2,3,4],[2,3,4,5],[3,4,5,6]]
print list(itertools.chain(*mylist))

Answer 2

mylist_n = [j for i in mylist for j in i]