Replace String

To replace a string, you should use the replace() method. This replaces a string with an other string. Here's an example:

a = "Hello, World!"
print(a.replace("H", "J"))

So on the example above, we are telling Python to replace the character H with the character J .

Question

What if that character exists multiple times in the string, how do you choose which one to change? Still need to find out.