def modify_event_subscription(SubscriptionName=None, SnsTopicArn=None,
    SourceType=None, EventCategories=None, Enabled=None):
    """
    Modifies an existing RDS event notification subscription. Note that you cannot modify the source identifiers using this call; to change source identifiers for a subscription, use the  AddSourceIdentifierToSubscription and  RemoveSourceIdentifierFromSubscription calls.
    You can see a list of the event categories for a given SourceType in the Events topic in the Amazon RDS User Guide or by using the DescribeEventCategories action.
    See also: AWS API Documentation
    
    Examples
    This example changes the specified setting for the specified event notification subscription.
    Expected Output:
    
    :example: response = client.modify_event_subscription(
        SubscriptionName='string',
        SnsTopicArn='string',
        SourceType='string',
        EventCategories=[
            'string',
        ],
        Enabled=True|False
    )
    
    
    :type SubscriptionName: string
    :param SubscriptionName: [REQUIRED]
            The name of the RDS event notification subscription.
            

    :type SnsTopicArn: string
    :param SnsTopicArn: The Amazon Resource Name (ARN) of the SNS topic created for event notification. The ARN is created by Amazon SNS when you create a topic and subscribe to it.

    :type SourceType: string
    :param SourceType: The type of source that will be generating the events. For example, if you want to be notified of events generated by a DB instance, you would set this parameter to db-instance. if this value is not specified, all events are returned.
            Valid values: db-instance | db-parameter-group | db-security-group | db-snapshot
            

    :type EventCategories: list
    :param EventCategories: A list of event categories for a SourceType that you want to subscribe to. You can see a list of the categories for a given SourceType in the Events topic in the Amazon RDS User Guide or by using the DescribeEventCategories action.
            (string) --
            

    :type Enabled: boolean
    :param Enabled: A Boolean value; set to true to activate the subscription.

    :rtype: dict
    :return: {
        'EventSubscription': {
            'CustomerAwsId': 'string',
            'CustSubscriptionId': 'string',
            'SnsTopicArn': 'string',
            'Status': 'string',
            'SubscriptionCreationTime': 'string',
            'SourceType': 'string',
            'SourceIdsList': [
                'string',
            ],
            'EventCategoriesList': [
                'string',
            ],
            'Enabled': True|False,
            'EventSubscriptionArn': 'string'
        }
    }
    
    
    :returns: 
    (string) --
    
    """
    pass
