function basic_dump2(o)
	if type(o) == "number" then
		return tostring(o)
	elseif type(o) == "string" then
		return string.format("%q", o)
	elseif type(o) == "boolean" then
		return tostring(o)
	elseif type(o) == "function" then
		return "<function>"
	elseif type(o) == "userdata" then
		return "<userdata>"
	elseif type(o) == "nil" then
		return "nil"
	else
		error("cannot dump a " .. type(o))
		return nil
	end
end

function dump2(o, name, dumped)
	name = name or "_"
	dumped = dumped or {}
	io.write(name, " = ")
	if type(o) == "number" or type(o) == "string" or type(o) == "boolean"
			or type(o) == "function" or type(o) == "nil"
			or type(o) == "userdata" then
		io.write(basic_dump2(o), "\n")
	elseif type(o) == "table" then
		if dumped[o] then
			io.write(dumped[o], "\n")
		else
			dumped[o] = name
			io.write("{}\n") -- new table
			for k,v in pairs(o) do
				local fieldname = string.format("%s[%s]", name, basic_dump2(k))
				dump2(v, fieldname, dumped)
			end
		end
	else
		error("cannot dump a " .. type(o))
		return nil
	end
end

function dump(o, dumped)
	dumped = dumped or {}
	if type(o) == "number" then
		return tostring(o)
	elseif type(o) == "string" then
		return string.format("%q", o)
	elseif type(o) == "table" then
		if dumped[o] then
			return "<circular reference>"
		end
		dumped[o] = true
		local t = {}
		for k,v in pairs(o) do
			t[#t+1] = "" .. k .. " = " .. dump(v, dumped)
		end
		return "{" .. table.concat(t, ", ") .. "}"
	elseif type(o) == "boolean" then
		return tostring(o)
	elseif type(o) == "function" then
		return "<function>"
	elseif type(o) == "userdata" then
		return "<userdata>"
	elseif type(o) == "nil" then
		return "nil"
	else
		error("cannot dump a " .. type(o))
		return nil
	end
end

--
-- Built-in node types. Also defined in C.
--

minetest.register_node("air", {
	drawtype = "airlike",
	paramtype = "light",
	light_propagates = true,
	sunlight_propagates = true,
	walkable = false,
	pointable = false,
	diggable = false,
	buildable_to = true,
	air_equivalent = true,
})

minetest.register_node("ignore", {
	drawtype = "airlike",
	paramtype = "none",
	light_propagates = false,
	sunlight_propagates = false,
	walkable = false,
	pointable = false,
	diggable = false,
	buildable_to = true, -- A way to remove accidentally placed ignores
	air_equivalent = true,
})