code: def get_current_release(self):
          
          current = self._runner.run("readlink '{0}'".format(self._current))
          if current.failed:
              return None
          return os.path.basename(current.strip())
docs: Get the release ID of the "current" deployment, None if
          there is no current deployment.
  
          This method performs one network operation.
  
          :return: Get the current release ID
          :rtype: str