code: def chown(self, path, user='', group=''):
          
          _complain_ifclosed(self.closed)
          return self.fs.chown(path, user, group)
docs: Change file owner and group.
  
          :type path: str
          :param path: the path to the file or directory
          :type user: str
          :param user: Hadoop username. Set to '' if only setting group
          :type group: str
          :param group: Hadoop group name. Set to '' if only setting user
          :raises: :exc:`~exceptions.IOError`