function has_neighbour_with_name(pos, name)
     for x = -1, 1, 1 do
            for y = -1, 1, 1 do
                 for z = -1, 1, 1 do
                        local pos0 = { x = pos.x + x,
                                                     y = pos.y + y,
                                                     z = pos.z + z }
                        if pos.x ~= pos0.x or pos.y ~= pos0.y or pos.z ~= pos0.z then
                             local node = minetest.get_node_or_nil(pos0)
                             if node and node ~=nil and node.name ~= nil and node.name == name then
                                    return true
                             end
                        end
                 end
            end
     end

     return false
end

bulb_node_base =
{
    groups = {snappy=1,choppy=2,oddly_breakable_by_hand=2,flammable=3},
    on_construct =
        function(pos)
             -- schedule timer
             minetest.get_node_timer(pos):start(0.1)
        end,

    on_destruct =
        function(pos)
             minetest.get_node_timer(pos):stop()
        end,

    on_timer =
        function(pos, elapsed)
             local self = minetest.get_node_or_nil(pos)

             if has_neighbour_with_name(pos, "tutorial:bulb") or
                  has_neighbour_with_name(pos, "tutorial:bulb_shine") then
                    if self.name ~= "tutorial:bulb_shine" then
                         minetest.add_node(pos, {name="tutorial:bulb_shine"})
                         return
                    end
             else
                    if self.name ~= "tutorial:bulb" then
                         minetest.add_node(pos, {name="tutorial:bulb"})
                         return
                    end
             end

             -- re-schedule timer
             minetest.get_node_timer(pos):start(0.1)
        end,
}

bulb_node = bulb_node_base
bulb_node.tiles =
{
  "tutorial_1.png",
  "tutorial_2.png",
  "tutorial_3.png",
  "tutorial_4.png",
  "tutorial_5.png",
  "tutorial_6.png"
}
minetest.register_node("tutorial:bulb", bulb_node)

bulb_shine_node = bulb_node_base
bulb_shine_node.tiles = {"tutorial_light.png"}
bulb_shine_node.light_source = 14
minetest.register_node("tutorial:bulb_shine", bulb_shine_node)


minetest.register_craft({
    output = 'tutorial:bulb 99',
    recipe = {
        {'default:wood', 'default:stone', ''},
        {'',             '',              ''},
        {'',             '',              ''},
    }
})