io.stdout:write("appender.lua greets you!\n")
io.stdout:flush()

function apply_filter(super)
    local ret = copy_super(super)
    ret.recv = function(sock)
            local line, err = super:recv()
            if line == nil then return line, err end
            return "Received: "..line
        end
    ret.send = function(sock, buf) super:send("Sending: "..buf) end
    return ret
end