code: def get_storage():
      
      storage_ = getattr(g, '_storage', None)
      if storage_ is None:
          storage_type = current_app.config['STORAGE_TYPE']
          if storage_type == 'file':
              storage_ = g._storage = storages.FileStorage()
          else:
              raise ConfigurationError(
                  'Storage type "{}" is not supported.'.format(storage_type))
      return storage_
docs: Get storage object of current app context,
      will create a new one if not exists.
  
      :return: a storage object
      :raise: ConfigurationError: storage type in config is not supported