Just a note because I saw a comment earlier about this: This is how mixins on python work. You need to put the concrete class as the last parameter of the class definition. The comment is definitely still helpful though.

I would suggest full sentences instead of point form though (this is from PEP8). Something like this might be more readable:

This Mixin marks an object as deleted by setting the deleted field to the current time. This should be mixed in with a `SingleObjectBaseView` and needs to precede a `generics.RetrieveDestroyAPIView` in the class definition.