entity Video in [Account, Album];
entity User in [UserGroup];
entity UserGroup;
entity Administrator;
entity Photo in [Account, Album];
entity Album in [Account];
entity Account;

action listPhotos
  appliesTo { principal: [User], resource: [Album, Photo, Video] };
action view, delete, edit
  appliesTo { principal: [User], resource: [Photo, Video, Album] };