diff --git a/README.md b/README.md
index 378abd7..90bd785 100644
--- a/README.md
+++ b/README.md
@@ -80,5 +80,6 @@ Textures: CC0
 - 2019-10-25  v1.6  * callback 'tubelib2_on_update2' added
 - 2020-01-03  v1.7  * max_tube_length bugfix
 - 2020-02-02  v1.8  * 'special nodes' as alternative to 'secondary nodes' introduced
+- 2020-05-31  v1.9  * Generator function 'get_tube_line' added, storage improvements
 
 
diff --git a/init.lua b/init.lua
index 88d4420..40ca46f 100644
--- a/init.lua
+++ b/init.lua
@@ -9,4 +9,4 @@ dofile(MP .. "/internal1.lua")
 dofile(MP .. "/tube_api.lua")
 dofile(MP .. "/storage.lua")
 -- Only for testing/demo purposes
---dofile(MP .. "/tube_test.lua")
+dofile(MP .. "/tube_test.lua")
diff --git a/internal2.lua b/internal2.lua
index dffbfb0..acee684 100644
--- a/internal2.lua
+++ b/internal2.lua
@@ -97,9 +97,9 @@ end
 -- Function returns param2, new_pos or nil
 function Tube:get_primary_node_param2(pos, dir)
 	local npos = vector.add(pos, Dir6dToVector[dir or 0])
-	local node = self:get_node_lvm(npos)
-	if self.primary_node_names[node.name] then
-		return node.param2, npos
+	self.node = self:get_node_lvm(npos)
+	if self.primary_node_names[self.node.name] then
+		return self.node.param2, npos
 	end
 end
 
diff --git a/storage.lua b/storage.lua
index 1a2dd80..883840c 100644
--- a/storage.lua
+++ b/storage.lua
@@ -42,6 +42,25 @@ end)
 
 minetest.after(600, update_mod_storage)
 
+local function empty_block(block)
+	local empty = true
+	local tbl = minetest.deserialize(block)
+	for k,v in pairs(tbl) do
+		if k ~= "used" and k ~= "best_before" then
+			empty = false
+		end
+	end
+	return empty
+end
+	
+minetest.after(1, function()
+	local tbl = storage:to_table()
+	for k,v in pairs(tbl.fields) do
+		if empty_block(v) then
+			storage:set_string(k, "")
+		end
+	end	
+end)
 
 --
 -- Local helper functions
@@ -118,7 +137,7 @@ function tubelib2.walk_over_all(clbk)
 			if mem then
 				if node_key ~= "used" and node_key ~= "best_before" then
 					local pos = keys_to_pos(block_key, node_key)
-					local node = techage.get_node_lvm(pos)
+					local node = tubelib2.get_node_lvm(pos)
 					clbk(pos, node, mem)
 				end
 			end
diff --git a/tube_api.lua b/tube_api.lua
index e4028ce..8a78ba9 100644
--- a/tube_api.lua
+++ b/tube_api.lua
@@ -13,7 +13,7 @@
 ]]--
 
 -- Version for compatibility checks, see readme.md/history
-tubelib2.version = 1.8
+tubelib2.version = 1.9
 
 -- for lazy programmers
 local S = function(pos) if pos then return minetest.pos_to_string(pos) end end
@@ -48,6 +48,24 @@ local function get_pos(pos, dir)
 end
 tubelib2.get_pos = get_pos
 
+function tubelib2.get_node_lvm(pos)
+	local node = minetest.get_node_or_nil(pos)
+	if node then
+		return node
+	end
+	local vm = minetest.get_voxel_manip()
+	local MinEdge, MaxEdge = vm:read_from_map(pos, pos)
+	local data = vm:get_data()
+	local param2_data = vm:get_param2_data()
+	local area = VoxelArea:new({MinEdge = MinEdge, MaxEdge = MaxEdge})
+	local idx = area:index(pos.x, pos.y, pos.z)
+	node = {
+		name = minetest.get_name_from_content_id(data[idx]),
+		param2 = param2_data[idx]
+	}
+	return node
+end
+
 local function update1(self, pos, dir)
 	local fpos,fdir = self:walk_tube_line(pos, dir)
 	self:infotext(get_pos(pos, dir), fpos)
@@ -381,3 +399,21 @@ end
 function Tube:switch_tube_line(pos, dir, state)
 	self:switch_nodes(pos, dir, state)
 end
+
+-- Generator function to iterate over a tube line
+-- Returns for each tube: i , pos, node
+function Tube:get_tube_line(pos, dir)
+	if pos and dir then
+		self.ref = {pos = pos, dir = dir}
+		return function(self, i)
+			if i < self.max_tube_length then
+				local new_pos, new_dir, num = self:get_next_tube(self.ref.pos, self.ref.dir)
+				if new_pos then
+					self.ref.pos, self.ref.dir = new_pos, new_dir
+					i = i + 1
+					return i, self.ref.pos, self.node
+				end
+			end
+		end, self, 0
+	end
+end	
diff --git a/tube_test.lua b/tube_test.lua
index 73a62b9..d6de452 100644
--- a/tube_test.lua
+++ b/tube_test.lua
@@ -45,6 +45,9 @@ Tube:register_on_tube_update(function(node, pos, out_dir, peer_pos, peer_in_dir)
 		print(S(pos).." to the "..sdir..": Connected with "..node.name.." at "..S(peer_pos).."/"..peer_in_dir)
 	else
 		print(S(pos).." to the "..sdir..": Connected with "..S(peer_pos).."/"..peer_in_dir)
+		for i, pos, node in Tube:get_tube_line(pos, out_dir) do
+			print("walk", S(pos), node.name)
+		end
 	end
 end)