This is the Python built-in tkinter module, except supplied separately.
It is useful when using a build of Python that does not have tkinter included, such as in a virtual environment on an Ubuntu installation without python3-tk.
Documentation: https://docs.python.org/3/library/tkinter.html
To build the wheel, just type:
python setup.py bdist_wheel
On Windows and macOS, the dependencies are copied automatically.
On Linux, you need to use auditwheel to do this, but see the included
build_manylinux.sh script.
The tkinter directory is lifted from the Python source, so its license is
that of the Python source (Python Software Foundation license).