# Validate new key if not self.key_validator.validate(new_key): return "Invalid new registration key"

# Placeholder for key validation logic class KeyValidator: def validate(self, key): # Logic to validate the key (e.g., format, hasn't been used before) return True

# Placeholder for user database interactions class UserDatabase: def get_registration_key(self, username): # Retrieve registration key for a given user pass