             materials: []
     else if icon.src.endsWith("image.gif")
         material = new Material
-            _id: activity.id,
+            _id: id,
             order: order,
             type: "image",
             indent: indent

    return
        material: material
        tree: tree

getProblem = (href, order) ->
    document = await downloadAndParse(href)

        indent -= 20
    return indent

getPageContent = (href) ->
    document = await downloadAndParse(href)
    data = document.getElementById("content")
