I have a question about python swap like `a, b = b, a`

.

Actually, the following is the solution code of EPI Python 5.10: apply_permutation.py

```
def apply_permutation(perm: List[int], A: List[int]) -> None:
for i in range(len(A)):
while perm[i] != i:
A[perm[i]], A[i] = A[i], A[perm[i]]
perm[perm[i]], perm[i] = perm[i], perm[perm[i]]
```

But, at the first time, I wrote the last line like this, (the order is different)

`perm[i], perm[perm[i]] = perm[perm[i]], perm[i]`

then, the result was different !

Can anyone tell me why ?

I tried to find solution in internet but, I even donâ€™t know the key word for this issue.

Thank you.