Python List

>>> a = [0, 0, 0]
>>> b = [a] * 3
>>> b
[[0, 0, 0], [0, 0, 0], [0, 0, 0]]
>>> b[0][0] = 1
>>> b
[[1, 0, 0], [1, 0, 0], [1, 0, 0]]
>>>

list is mutable, and the multiplication with a scalar will copy the reference rather than the real memory.