main.py

import argparse
from . import user_service, doc_service, repo_service

parser = argparse.ArgumentParser()
# ... set argument

args = parser.parse_args()
print(getattr(
    globals()[f'{args.sub}_service'],
    getattr(args, args.sub))
      (**vars(args)))

user_service.py

# -*- coding: utf-8 -*-

def update(id_, name, **_):
    return f'{id_}, {name}'