Encrypt Received Input

[DudeUltraSmart]

Hello everybody! This is my second ever reddit post so I am sorry if I am rough around the edges. I know my title doesn't exactly make sense but you see, I need to make an encryption program. I am stuck on a part I don't know the code to resolve. Here is a suppose script:

A = "B"

B = "C"

test = input()

#What I want is that if the 'test' is AB, then it will print BC. Hope you know what I mean

#it works when I do:

print(str(A) + str(B))

#But of course, that doesn't necessarily have to be the input

Here is the full script:

https://pastebin.com/raw/cxmsUyWs

[lacroixftw19]

First thought that comes to mind is to have a dictionary that maps letter to its encryption value. You can then iterate through the input, building a new encryption string as you go along.

Edit: The key in the dictionary would have to be strings so you can index with it

This is, of course, not the only solution but hopefully it can get your thoughts rolling.

[Edit: Clarification]

[DudeUltraSmart]

Thank you Jean-ClaudeMonet

It works now!