A robot that implements BorderSentry is a robot type used for keeping other robots away from the borders,
i.e. guarding the borders in order to prevent "wall crawlers".
Robots that implement BorderSentry have 400 extra life/energy (500 in total), but is placed at the border
of the battlefield when the game is started.
Border sentry robots cannot move away from the border area, and they can only make damage to robots that
are moving into the border area. The size of the border area is determined by the
battle rules.
This type of robot is intended for use in battles where robots should be forced away from the borders
in order to prevent "wall crawlers".
Border sentry robots does not get scores, and will not occur in the battle results or rankings.