>>>a = {1: [1,2,3]}
>>> b = a.copy()
>>> a, b({1: [1, 2, 3]}, {1: [1, 2, 3]})
>>> a[1].append(4)
>>> a, b({1: [1, 2, 3, 4]}, {1: [1, 2, 3, 4]})
>>>import copy
>>> c = copy.deepcopy(a)
>>> a, c({1: [1, 2, 3, 4]}, {1: [1, 2, 3, 4]})
>>> a[1].append(5)
>>> a, c({1: [1, 2, 3, 4, 5]}, {1: [1, 2, 3, 4]})
