docs: public Set<Tile> getNeighbours() {
          Set<Tile> neighbours = new HashSet<Tile>(8);
          neighbours.add(getLeft());
          neighbours.add(getAboveLeft());
          neighbours.add(getAbove());
          neighbours.add(getAboveRight());
          neighbours.add(getRight());
          neighbours.add(getBelowRight());
          neighbours.add(getBelow());
          neighbours.add(getBelowLeft());
          return neighbours;
      }