app engine ndb - how to load entity by key using id?

YourModel.get_by_id() gets a model instance by id.

here the docs:
https://developers.google.com/appengine/docs/python/ndb/modelclass#Model_get_by_id

don't think you can't get an entity by id without knowing the kind because instances of different Model classes can have the same id/key_name

Another way: ndb.Key(YourModel, id).get().