I am new to python.
I want to shift char by its position. for e.g.

pos= 3 then replace c by z , b by y , a by x, Same like C by Z , B by Y and A by X

What I have tried ?
I have tried with hardcoded values as,

```
for i in s:
     if ord(i) == 99:
          return z
     if ord(i) == 98:
          return x
     ...
     ...

```

Is there is any builtin function is available to do this ? or Any other simpler way to achieve this ?

**Edit:**

if string would be `"abcdef"`
the output would be `"xyzabc"`

I user input `"AbCdEf"` then output would be `"XyZaBc"`