I've registered the [flask-mongoengine](https://github.com/MongoEngine/flask-mongoengine) extension in my Flask app and initialized it. 

I now want to access its `conn` property as I want to do pure MongoDB queries too.

```
>> app.extensions
{'csrf': <flask_wtf.csrf.CSRFProtect object at 0x00000213B72AB940>,
 'mail': <flask_mail._Mail object at 0x00000213B72ABCF8>,
 'mongoengine': {
     <flask_mongoengine.MongoEngine object at 0x00000213B72ABDD8>: {
         'app': <Flask 'app'>,
         'conn': MongoClient(host=['xxx'], document_class=dict, tz_aware=False, connect=True, ssl=True, replicaset='Cluster0-shard-0', authsource='admin', retrywrites=True, read_preference=Primary())
     }
  },
  'rq2': <flask_rq2.app.RQ object at 0x00000213B5DE8940>,
  'security': <flask_security.core._SecurityState object at 0x00000213B734EE10>
}

```

Is there a way to access the `conn` property other than the very convoluted (and error-prone):

```
>> list(app.extensions.get('mongoengine').values())[0].get('conn')
MongoClient(host=['xxx'], document_class=dict, tz_aware=False, connect=True, ssl=True, replicaset='Cluster0-shard-0', authsource='admin', retrywrites=True, read_preference=Primary())

```

Does flask-mongoengine have a method to access its properties?