def neighbours
      offsets = (-1..1).to_a.product((-1..1).to_a)
      offsets.map do |lat, lng|
        begin 
          neighbour(lat:lat, lng:lng)
        rescue ArgumentError
          nil # occurs on world boundaries
        end
      end.compact
    end
def neighbours
      offsets = (-1..1).to_a.product((-1..1).to_a)
      offsets.map do |lat, lng|
        begin 
          neighbour(lat:lat, lng:lng)
        rescue ArgumentError
          nil # occurs on world boundaries
        end
      end.compact
    end
return neighbouring tiles to the north, northeast, and east