from copy import deepcopy
#1
sth1 = [[1, 2, 3], [2, 3, 4]]
sth2 = sth1[:]
sth2[0] = [7, 8, 9]
print(sth1)
print(sth2)

#2
sth1 = [[1, 2, 3], [2, 3, 4]]
sth2 = sth1[:]
sth2[0][0] = 'something_deep'
print(sth1)
print(sth2)

#3
sth1 = [[1, 2, 3], [2, 3, 4]]
sth2 = deepcopy(sth1)
sth2[0][0] = 'something_deep'
print(sth1)
print(sth2)