Best approach to extend classes but use a specific method as entrypoint for super class

Question

So I'm looking into having a main class that defines a specific method and an extended class that adds some functionality to that method, such as:

class SuperClass:
    def __init__(self):
        self._data = {}

    @abc.abstractmethod
    def _get_obj(self, id):
        pass

    def get(self,  obj_id):
        # do stuff that should be done for all methods, eg.
        if obj_id not in self.data:
            obj= self._get_obj(obj_id)
            self.data[obj_id] = obj              
        return self.data[obj_id]

class SubClass(SuperClass):
    def _get_obj(self, obj_id):
        pass

The idea is that the get method is the only "public" one. Is there a better way to do this? For clarity I've only shown one of the "public" methods, but there may be many.

For reference, this is using Python 3.6. And any other comments regarding the code are welcome.

Update (also code cleanup): Another approach is to use super to call the original get which may be clearer, but forces the coder to always need to add the call there:

class SuperClass:
    def __init__(self):
        self._data = {}

    def get(self,  obj_id):
        # do stuff that should be done for all methods, eg.
        if obj_id in self.data:
            return self.data[obj_id]
        pass                


class SubClass(SuperClass):
    def get_from_db(self, obj_id):
        # Code to get from db
        return obj

    def get(self, obj_id):
        obj = super().get(obj_id
        if None:
            obj= self.get_from_db(obj_id)
            self.data[obj_id] = obj  
        return obj