def update_subscriber(AccountId=None, BudgetName=None, Notification=None,
    OldSubscriber=None, NewSubscriber=None):
    """
    Update a subscriber
    See also: AWS API Documentation
    
    
    :example: response = client.update_subscriber(
        AccountId='string',
        BudgetName='string',
        Notification={
            'NotificationType': 'ACTUAL'|'FORECASTED',
            'ComparisonOperator': 'GREATER_THAN'|'LESS_THAN'|'EQUAL_TO',
            'Threshold': 123.0
        },
        OldSubscriber={
            'SubscriptionType': 'SNS'|'EMAIL',
            'Address': 'string'
        },
        NewSubscriber={
            'SubscriptionType': 'SNS'|'EMAIL',
            'Address': 'string'
        }
    )
    
    
    :type AccountId: string
    :param AccountId: [REQUIRED] Account Id of the customer. It should be a 12 digit number.

    :type BudgetName: string
    :param BudgetName: [REQUIRED] A string represents the budget name. No ':' character is allowed.

    :type Notification: dict
    :param Notification: [REQUIRED] Notification model. Each budget may contain multiple notifications with different settings.
            NotificationType (string) -- [REQUIRED] The type of a notification. It should be ACTUAL or FORECASTED.
            ComparisonOperator (string) -- [REQUIRED] The comparison operator of a notification. Currently we support less than, equal to and greater than.
            Threshold (float) -- [REQUIRED] The threshold of the a notification. It should be a number between 0 and 100.
            

    :type OldSubscriber: dict
    :param OldSubscriber: [REQUIRED] Subscriber model. Each notification may contain multiple subscribers with different addresses.
            SubscriptionType (string) -- [REQUIRED] The subscription type of the subscriber. It can be SMS or EMAIL.
            Address (string) -- [REQUIRED] A generic String.
            

    :type NewSubscriber: dict
    :param NewSubscriber: [REQUIRED] Subscriber model. Each notification may contain multiple subscribers with different addresses.
            SubscriptionType (string) -- [REQUIRED] The subscription type of the subscriber. It can be SMS or EMAIL.
            Address (string) -- [REQUIRED] A generic String.
            

    :rtype: dict
    :return: {}
    
    
    :returns: 
    (dict) -- Response of UpdateSubscriber
    
    """
    pass
