             }
            });
        }
    }

    function pageChanged() {
        var logos = document.querySelectorAll(".nats");
        if (logos && logos.length == 0) {
            gitbook.toolbar.createButton({
                icon: 'nats',
                label: 'NATS Home Page',
                position: 'right',
                onClick: function () {
                    var win = window.open("https://nats.io/", '_blank');
                    win.focus();
                }
            });
        }