How to drag and drop in Marmalade Quick (Lua), code fragment (incomplete)

howDraqDropCodeFragmentInMQuick.lua

--https://devnet.madewithmarmalade.com/questions/3537/drag-and-drop-marmalade-quick.html

local box = director:createRectangle(director.displayCenterX, director.displayCenterY, 100, 100)
box.color = color.green
 
function box:touch(event)
    if event.phase == "began" then
        self.color = color.red
        box.xLast = event.x
        box.yLast = event.y
    elseif event.phase == "ended" then
        self.color = color.green
    elseif event.phase == "moved" then
        local dx = event.x - self.xLast
        local dy = event.y - self.yLast
        self.x = self.x + dx
        self.y = self.y + dy
        box.xLast = event.x
        box.yLast = event.y
    end
end
 
box:addEventListener("touch", box)