I found this confectionery at a convenience store in Phimai, Thailand (map) .
I wonder if the manufacturer has licensed the trademark from The Open Group.
>>> from verhoeff import VerhoeffAlternatively, it can be invoked as a command as follows:
>>> v = Verhoeff()
>>> v.calcsum(142857)
0
>>> v.checksum(1428570)
0
python verhoeff.py 142857
1428570