docs: def list_dir(self):
          """
          Non-recursive file listing.
  
          :returns: A generator over files in this "directory" for efficiency.
          """
  
          bucket = self.blob.bucket
          prefix = self.blob.name
          if not prefix.endswith('/'): prefix += '/'
  
          for blob in bucket.list_blobs(prefix=prefix, delimiter='/'):
              yield 'gs://{}/{}'.format(blob.bucket.name, blob.name)