def beforeFrame(scene):
    scn = bpy.context.scene
    for itm in bpy.data.objects:
        print(itm.name)
        print(itm.data.name)
    curr = scn.frame_current
    strt = scn.frame_start
    end = scn.frame_end
    num = end -strt


    ob = scn.objects.active
    ob.layers[0] = False
    # you may add it to any other layer:
    ob.layers[4] = True


    old_select = scn.objects.active
    old_select.select = False
    print(old_select)
    print(scn.objects.active.select)

    for itm in bpy.data.objects:
        if "Subdiv" in itm.name:
            msh = itm.data
            itm.select = True

            print("selected objects")

            print(itm.name)

            bpy.ops.object.delete()
            obj = bpy.data.objects.get(itm.name)
            print(obj)
            itm.select = False
            bpy.data.meshes.remove(msh)

    time = float(curr -strt)/num

    old_select.select = True

    origMesh = old_select.data
    catmullClark(origMesh,numSubdiv,time,curr)
    #elapsed time in [0,1]