docs: def execute_cmd(self, *args, **kwargs):
          """Execute a given hpssacli/ssacli command on the controller.
  
          This method executes a given command on the controller.
  
          :params args: a tuple consisting of sub-commands to be appended
              after specifying the controller in hpssacli/ssacli command.
          :param kwargs: kwargs to be passed to execute() in processutils
          :raises: HPSSAOperationError, if hpssacli/ssacli operation failed.
          """
          slot = self.properties['Slot']
          base_cmd = ("controller", "slot=%s" % slot)
          cmd = base_cmd + args
          return _ssacli(*cmd, **kwargs)