MarsSeed [1] filed a deletion request for python2-latlon [2]: Seems to be an unused Python2 package, from 2016.
Upstream's last release was in 2014. There's a Python3 fork on PyPI: latlon3. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/python2-latlon/
