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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _get_ctypes(self):
 """ Returns all related objects for this model. """

        ctypes = []
        for related_object in self.model._meta.get_all_related_objects():
            model = getattr(related_object, 'related_model', related_object.model)
            ctypes.append(ContentType.objects.get_for_model(model).pk)
            if model.__subclasses__():
                for child in model.__subclasses__():
                    ctypes.append(ContentType.objects.get_for_model(child).pk)
        return ctypes