User existence check

Can you use one of the following functions based on the requirement?

1. isuseractive - Returns true if a given username represents an active user account.
2. isusernametaken - Returns true if a user (active or deactivated) with the specified username (case-sensitive) exists in the system, indicating that the username is taken. Returns false otherwise.
3. isusernameavailablefornewaccount - Returns whether a username can be used to create a new account

Thank you brother

Welcome :)