* and end/out we have to handle all the border cases correctly.
* Each node is in its own red_reachable set (see calculation
* function above). That means, that in the case where bl == t, the
* and end/out we have to handle all the border cases correctly.
* Each node is in its own red_reachable set (see calculation
* function above). That means, that in the case where bl == t, the