Why does Debian 11 on my Chromebook refuse to allow Python 3 .11 with Tkinter to run "root = Tk()", returning "No protocol specified"

I installed Debian 11 Bullseye on my Chromebook, and I thought I'd try out a sample program from the Python.org tutorial about Tkinter. It failed at the first line after the imports; I got the following error message:

python
No protocol specified

Traceback (most recent call last):
  File "", line 1, in 
  File "/usr/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 ":0"

I don't quite know what to do when the code from Python.org doesn't run...The last part of the message seems to implicate X, but everything else writes to the screen quite handily, even though .Xauthority does not exist. Any help would be appreciated.