Python a, b = b, a背后的故事

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a = [1,2,3,4,5,6]
x = 0
a[x] = 1
a[a[x]] = 2
a[x], a[a[x]] = a[a[x]], a[x]    # 实质执行了  xxx = a[a[x]], a[x]   ;  a[x], a[a[x]] = xxx
print(a)  # [2, 2, 1, 4, 5, 6]


c, d = 1, 2
c, d = d, c + d  # 实质执行了  xxx = d, c + d  ;  c,d = xxx
print(c, d)  # 2 3