def response_message(resp_json):
    """Pulls the error message out of a Waiter response"""
    if 'waiter-error' in resp_json and 'message' in resp_json['waiter-error']:
        message = resp_json['waiter-error']['message']
        if not message.endswith('.'):
            message = f'{message}.'
    else:
        message = 'Encountered unexpected error.'
    return message