+public interface PostDatabase {
+
+ Function<String, Optional<Post>> getPost();
+
+ /**
+ * Returns the post with the given ID.
+ *
+ * @param postId
+ * The ID of the post to return
+ * @return The post with the given ID, or {@code null}
+ */
+ Optional<Post> getPost(String postId);
+
+ /**
+ * Returns all posts from the given Sone.
+ *
+ * @param soneId
+ * The ID of the Sone
+ * @return All posts from the given Sone
+ */
+ Collection<Post> getPosts(String soneId);