How to set to come back the charger closest to the finishing point after task "loop" (#397)

Posted by @miharaka:

I would like to ask the continuation of the following github issue.

As the answer to this issue, I would like to use an API “set_charger_waypoint” Just before the loop task end, and want the robot to come back the empty charger closest to the waypoint at which the task ends.

Please how to solve this problem. Or, are there any manuals?