public static boolean isEntrance(Tile t) {
    for (Tile n : t.edgeAdjacent(tempT4)) {
      if (n == null || ! (n.owner() instanceof Boardable)) continue ;
      for (Boardable b : ((Boardable) n.owner()).canBoard(tempB4)) {
        if (b == t) return true ;
      }
    }
    return false ;
  }