def delete_matching_files_from_storage(self, root_folder, regex):
        directory_list, file_list = self.storage.listdir(root_folder)
        for f in file_list:
            if regex.match(f) is not None:
                file_location = os.path.join(root_folder, f)
                self.storage.delete(file_location)
                cache.delete(
                    self.storage.url(file_location)
                )
                print(
                    "Deleted {file} (created from: {original})".format(
                        file=os.path.join(root_folder, f),
                        original=self.name
                    )
                )
Deletes files from `root_folder` on self.storage that match
dataset/ETHPy150Open WGBH/django-versatileimagefield/versatileimagefield/mixins.py/VersatileImageMixIn.delete_matching_files_from_storage