public static void addFriendship(String username1, String username2) {
		User user1 = getUserByUsername(username1.trim());
		if (user1 == null) {
			System.out.println("User " + username1 + " NOT FOUND");
		}
		User user2 = getUserByUsername(username2.trim());
		if (user2 == null) {
			System.out.println("User " + username2 + " NOT FOUND");
		}
		user1.addFriend(user2);
	}