code: def version(self):
          
          if self._server_version is None:
              try:
                  data = self.http_get('/version')
                  self._server_version = data['version']
                  self._server_revision = data['revision']
              except Exception:
                  self._server_version = self._server_revision = 'unknown'
  
          return self._server_version, self._server_revision
docs: Returns the version and revision of the gitlab server.
  
          Note that self.version and self.revision will be set on the gitlab
          object.
  
          Returns:
              tuple (str, str): The server version and server revision.
                                ('unknown', 'unknwown') if the server doesn't
                                perform as expected.