def test_cool()
   forest = [ [0, 0, 0, 0, 0], [0, 0, 0, 0, 0], [1, 2, 3, 4, 4] ]
   for i in 0..forest.length-1 do
      for j in 0..forest[i].length-1 do
         print cool?(forest, i, j, 20), " "
      end
      print "\n"
   end
end