actionLib: what is `preempt` and how to use it?
I'm following the actionLib tutorial.
I found in both GoalCallbackMethod and ExecuteCallbackMethod tutorials, the server use either callbacks or isPreemptRequested to handle the preempt.
But I didn't find anything related to preempt in the client side.
So I'm wondering how the preempt works? How could I send a work to server and say it is a preempted work.