Replace letters in a string using Python -

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i'm new python , i'm trying understand basic thing. have code:

def mix_up(a, b):     a,b=b[0:2]+a[2:], a[0:3]+b[3:]     print (a,b)  mix_up("abcd","efgh")

why b doesn't "new" 3 letters of (i.e, "efch")? there elegant of doing in 1 line, or have use other variables?

thanks!

the reason not working because assignment (the left hand side of =) happens after entire right hand side evaluated.

so a , b still "old" a , b in statement, , not new ones.

to fix it, split 2 statements:

a = b[0:2]+a[2:] b = a[0:3]+b[3:]  # "new"

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