code: def __init__(self):
      super().__init__()
      self.callbacks = []
  
imports: from PyQt5 import QtCore, QtGui, QtWidgets, sip
  from PyQt5.QtCore import Qt
  from pandasgui.store import PandasGuiDataFrameStore, PandasGuiStore
  from pandasgui.widgets import base_widgets
  import tempfile
  import os
  from pandasgui.utility import traverse_tree_widget
  from pandasgui.widgets.column_viewer import FlatDraggableTree
  from pandasgui.widgets.json_viewer import JsonViewer
label_desc: Use image node_id 1 to create a new DelayedMimeData object from inherited base classes: QtCore with example: obj = DelayedMimeData()