def is_create_required(event):
    """
    Indicates whether a create is required in order to update.
    :param event: to check
    """
    if event['RequestType'] == 'Create':
        return True

    new = event['ResourceProperties']
    old = event['OldResourceProperties'] if 'OldResourceProperties' in event else new

    return old.get('Priority', 0) != new.get('Priority', 0) or old.get('ListenerArn', None) != new.get('ListenerArn',
                                                                                                       None)