which is the difference between the 2 codes

Question

Seems the same code but i get the different results

# code1

a = 0
b = 1
for i in range(0, 10):
    print(a)
    a = b
    b = a + b

# code2

a, b = 0, 1
for i in range(0, 10):
    print(a)
    a,b = b, a + b

a = 0
b = 1
for i in range(0, 10):
    print(a)
    a = b
    b = a + b

print()

a, b = 0, 1
for i in range(0, 10):
    print(a)
    a,b = b, a + b

I expected the same output

Answer 1

When you use the code 1 : first, a takes the value of b and then b become a+b, but with the new value of a.

In code 2, the evaluation of a and b is "simultaneous", as you use unpacking. In the same time, a takeb and b takes the value of a+b, but a still have his initial value.

Hope that I'm clear !