unfollow method Null safety

Future unfollow(
  1. String targetId
)

Unfollows a user whose objectId is targetId.

Implementation

Future unfollow(String targetId) async {
  if (isNullOrEmpty(targetId)) {
    throw ArgumentError.notNull('targetId');
  }
  String path = 'users/self/friendship/$targetId';
  await LeanCloud._httpClient.delete(path);
}