code: def get_resource_types(self):
          
          resource_types = set()
          for model in self.models():
              for field in self.model_file_fields(model):
                  resource_type = field.storage.RESOURCE_TYPE
                  resource_types.add(resource_type)
          return resource_types
docs: Returns set of resource types of FileFields of all registered models.
          Needed by Cloudinary as resource type is needed to browse or delete specific files.