red nodes are unreachable, orange nodes are indirectly reachable, green nodes are directly reachable.
Black nodes are either directly or indirectly reachable, but direct reachability has not been tried yet.
red nodes are unreachable, orange nodes are indirectly reachable, green nodes are directly reachable.
Black nodes are either directly or indirectly reachable, but direct reachability has not been tried yet.