XML example:
<Notification>
    <NotificationMetaData>
        <NotificationType>Test</NotificationType>
        <PayloadVersion>1.0</PayloadVersion>
        <UniqueId>7f8a6814-c41b-47d1-bde4-d83beaf9ba47</UniqueId>
        <PublishTime>2019-07-21T00:11:17Z</PublishTime>
        <SellerId>A1TEY33G76VT1J</SellerId>
    </NotificationMetaData>
    <NotificationPayload>
        <TestNotification />
    </NotificationPayload>
</Notification>

parsed dict example:
{
  'Notification': {
    'NotificationMetaData': {
      'NotificationType': 'Test',
      'PayloadVersion': '1.0',
      'UniqueId': '5d053e18-fe0e-4cee-8d8d-3f399c8e5bb2',
      'PublishTime': '2019-07-21T00:26:39Z',
      'SellerId': 'A1TEY33G76VT1J'
    },
    'NotificationPayload': {
      'TestNotification': None
    }
  }
}