def modify_event_subscription(SubscriptionName=None, SnsTopicArn=None,
    SourceType=None, EventCategories=None, Enabled=None):
    """
    Modifies an existing AWS DMS event notification subscription.
    See also: AWS API Documentation
    
    
    :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 AWS DMS event notification subscription to be modified.
            

    :type SnsTopicArn: string
    :param SnsTopicArn: The Amazon Resource Name (ARN) of the Amazon 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 AWS DMS resource that generates the events you want to subscribe to.
            Valid values: replication-instance | migration-task
            

    :type EventCategories: list
    :param EventCategories: A list of event categories for a source type that you want to subscribe to. Use the DescribeEventCategories action to see a list of event categories.
            (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
        }
    }
    
    
    :returns: 
    (string) --
    
    """
    pass
