a+=b应用于数组时与a=a+b不同

a+=b应用于数组时与a=a+b不同

a=[1,2]
b=[4,5]
b=a
b = b+[3]
print(a)
print(b)

[1, 2]
[1, 2, 3]

a=[1,2]
b=[4,5]
b=a
b += [3]
print(a)
print(b)

[1, 2, 3]
[1, 2, 3]