Favorite
Track which articles a user has favorited Each user maintains a set of favorited article references
Commands
favorite
Add article to user s favorites set Return user and article references
Arguments: $0 user (U), $1 article (string)
unfavorite
Remove article from user s favorites set Return user and article references
Arguments: $0 user (U), $1 article (string)
isFavorited
Return whether the article is in the user s favorites
Arguments: $0 user (U), $1 article (string)
count
Return the number of users who favorited this article
Arguments: $0 article (string)