Convert CamelCase to snake_case in Python

camel-snake.py

import re

def convert(name):
    s1 = re.sub(r"(.)([A-Z][a-z]+)", r"\1_\2", name)
    return re.sub(r"([a-z0-9])([A-Z])", r"\1_\2", s1).lower()

tests = ["CamelCase", "CamelCamelCase", "getHTTPResponseCode", 
    "getHTTPResponseCode", "HTTPResponseCodeXYZ"]

for test in tests:
    print(test, "=>", convert(test))