onUnfollow method
Handles updates to the feed state when an unfollow action occurs.
Implementation
void onUnfollow({required FeedId sourceFid, required FeedId targetFid}) {
// Remove the follow relationship between sourceFid and targetFid
final updatedFollowing = state.following.whereNot((it) {
var filter = it.sourceFeed.id == sourceFid.id;
return filter &= it.targetFeed.id == targetFid.id;
}).toList();
state = state.copyWith(following: updatedFollowing);
}