[PYTHON-312] Implementing slot_checkId for user registration | Checking for duplicate IDs | Using...
Implement the `slot_checkId` for user registration.
Learn how to check for duplicate IDs in stored user information using the `shelve` module.
If there are no duplicate IDs, call the method written in PYTHON-311 to check length information; if there are duplicate IDs, display an error message.
Use `try ~ except` together.