public ReturnObject registerUser(int id, String email, String password, String name)
        {
            CredentialService credentialService = new CredentialService();

            if (credentialService.credentialsValid(name, email, password))
            {
                if (userRepository.findByEmail(email) == null)
                {
                    userRepository.createHistory(id);
                    return(userRepository.create(id, name, email, password));
                }
                else
                {
                    return(new ReturnObject(false, "User already exists."));
                }
            }
            else
            {
                return(new ReturnObject(false, "Credentials are invalid."));
            }
        }