_tkinter.TclError: couldn't connect to display

[jesenzhang]

sys:
Distributor ID: Ubuntu
Description: Ubuntu 20.04.6 LTS
Release: 20.04
Codename: focal

run the simple code:
import easygui
easygui.ynbox('Shall I continue?', 'Title', ('Yes', 'No'))

report error:
Traceback (most recent call last):
File "/media/kohya_ss/tktest.py", line 2, in
easygui.ynbox('Shall I continue?', 'Title', ('Yes', 'No'))
File "/anaconda3/envs/comfy/lib/python3.11/site-packages/easygui/boxes/derived_boxes.py", line 54, in ynbox
return boolbox(msg=msg,
^^^^^^^^^^^^^^^^
File "/anaconda3/envs/comfy/lib/python3.11/site-packages/easygui/boxes/derived_boxes.py", line 133, in boolbox
reply = buttonbox(msg=msg,
^^^^^^^^^^^^^^^^^^
File /anaconda3/envs/comfy/lib/python3.11/site-packages/easygui/boxes/button_box.py", line 95, in buttonbox
bb = ButtonBox(
^^^^^^^^^^
File "/anaconda3/envs/comfy/lib/python3.11/site-packages/easygui/boxes/button_box.py", line 147, in init
self.ui = GUItk(msg, title, choices, images, default_choice, cancel_choice, self.callback_ui)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/anaconda3/envs/comfy/lib/python3.11/site-packages/easygui/boxes/button_box.py", line 263, in init
self.boxRoot = tk.Tk()
^^^^^^^
File "/anaconda3/envs/comfy/lib/python3.11/tkinter/init.py", line 2326, in init
self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_tkinter.TclError: couldn't connect to display ""