Hi Guix,
Python 2.7 doesn't seem like it handles Tk properly right now, at least on my machine:
>>> import Tkinter
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/gnu/store/h2crv1mpc5qi05xdnn84fjp9g4gyicsl-python2-2.7.16/lib/python2.7/lib-tk/Tkinter.py", line 39, in <module>
import _tkinter # If this fails your Python may not be configured for Tk
ImportError: No module named _tkinter