BP_Messages_Thread::is_valid( int $thread_id )

	public static function is_valid( $thread_id = 0 ) {

		// Bail if no thread ID is passed.
		if ( empty( $thread_id ) ) {
			return false;
		}

		$thread = self::get_messages( $thread_id );

		if ( ! empty( $thread ) ) {
			return $thread_id;
		} else {
			return null;
		}
	}