Strings are not mutable! (meaning you can't use indexing to change individual elements of a string). For Example, If you execute below code:
my_string = "ProgramsBuzz"
my_string[0] = "R"
You will get TypeError: 'str' object does not support item assignment.
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TypeError Traceback (most recent call last)
<ipython-input-69-0ede303df111> in <module>
----> 1 my_string[0] = "R"
TypeError: 'str' object does not support item assignment