if s == nil and e == nil then
    s = 1
    e = #Lines
  elseif e == nil then

  assert(s)
  if e == nil then

        Lines.current_drawing_index = line_index
        Lines.current_drawing = line
        Drawing.before = snapshot(line_index)

    save_to_disk(Lines, Filename)
    if Drawing.before then
      record_undo_event({before=Drawing.before, after=snapshot(Lines.current_drawing_index)})
      Drawing.before = nil
    end

  Drawing.before = snapshot()

  Lines.current_drawing = drawing

  save_to_disk(Lines, Filename)
  if Drawing.before then
    record_undo_event({before=Drawing.before, after=snapshot()})
    Drawing.before = nil
  end