在另一个列表python中解压缩列表

Question

假设你有一个清单：

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

任何pythonic（2.x）解压内部列表的方式，以便新列表看起来像？：

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]