I have the following code to register a user to firebase...

```
FIRAuth.auth()?.createUserWithEmail(email.text!, password: password.text!) {(user, error) in
            if let error = error {
                print(error.localizedDescription)
                if error.localizedDescription == "FIRAuthErrorCodeEmailAlreadyInUse"
                {
                   //sign in here?
                }

            }
            else {
                print("User signed in!")
            }
        } }
    else{
        print("You left email/password empty")
    }

```

What would I add to this so it automatically signs in if the user was already created?

Thanks.