Creating a python script for patterns

I would like to ask your help in creating a python code for my data.

I have a list of string "1. AGGCHRUSHCCKSGDSKCGGHCSG" I would like to get all "G" in my string and print a pattern pit like this: GG-G-GG-G and if there are no Gs in my string, it should print "No G found"

I have tried basic string, substring, and print in python, but that's all I got. I'm really new here. I'm sorry and thank you very much.