function try_lock( $expiration = 0 ) {
            if ( $this->is_locked() ) {
                // Already locked.
                return false;
            }

            set_site_transient( "locked_{$this->_wp_user_id}", $this->_thread_id, $expiration );

            if ( $this->has_lock() ) {
                set_site_transient( "locked_{$this->_wp_user_id}", true, $expiration );

                return true;
            }

            return false;
        }