MarsSeed [1] filed a deletion request for douban.fm [2]: Defunct Python 2 package, broken because of missing deps. Last release was in 2016, so it seems deprecated. Safe to delete; nothing depends on this package.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/douban.fm/
