How to send multiple data (conn:send()) with the new SDK (NodeMCU)

I've been reading the NodeMCU documentation and several closed issues about the change of SDK that previouly allowed to send multiple data streams (acting like a queued net.socket:send).

It seems a huge debate grew here (#730) and there (#993) or even here (#999). However, I did not find any convincing example of a webserver code that would allow me to read multiple html files (e.g. head.html and body.html) to display a page. Here's the example from TerryE that I tried to adapt, but with no success:

srv=net.createServer(net.TCP)
srv:listen(80,function(conn)
    conn:on ("receive", function(sck, req)
        local response = {}

        local f = file.open("head.html","r")
        if f ~= nil then
            response[#response+1] = file.read()
            file.close()
        end

        local f = file.open("body.html","r")
        if f ~= nil then
            response[#response+1] = file.read()
            file.close()
        end

        local function sender (sck)
            if #response>0 then sck:send(table.remove(response,1))
            else sck:close()
            end
        end
        sck:on("sent", sender)
        sender(sck)
    end )
end )

When connecting to the ESP8266, nothing loads and I get no error from the lua terminal.

For your information, head.html contains:

<html>
<head>
</head>

And body.html contains:

<body>
<h1>Hello World</h1>
</body>
</html>

I am very new to NodeMCU, please be tolerant.