docs: def _query(self, filename):
          """Get size of filename"""
          #  - Query metadata of one file
          #  - Return a dict with a 'size' key, and a file size value (-1 for not found)
          #  - Retried if an exception is thrown
          log.Info('Querying size of %s' % filename)
          from jottalib.JFS import JFSNotFoundError, JFSIncompleteFile
          remote_path = posixpath.join(self.folder.path, filename)
          try:
              remote_file = self.client.getObject(remote_path)
          except JFSNotFoundError:
              return {'size': -1}
          return {
              'size': remote_file.size,
          }