a = [1, 2, 3]
b = [4, 5, 6]

print(a + b)   # concatenation, NOT element-wise addition
print(a * 3)   # repeats the list, NOT element-wise multiplication

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