Unexpected feature in a Python list of lists

myList = [[1] * 4] * 3

[[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]

myList[0][0] = 5

[[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]

[[1]*4 for n in range(3)]

[[1] * 4] * 3

[[1, 1, 1, 1]] * 3

>>> inner = [1,1,1,1]
>>> outer = [inner]*3
>>> outer
[[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]
>>> inner[0] = 5
>>> outer
[[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]

lst = [[1] * 4] * 3

lst1 = [1]*4
lst = [lst1]*3

lst[0][0] = 5
lst1[0] = 5

lst = [ [1]*4 for n in xrange(3) ]