   if (xhr.readyState == 4) {

                    if (xhr.status < 400 && xhr.responseText) {
                        code.textContent = xhr.responseText;

                        Prism.highlightElement(code);
                    }
                    else if (xhr.status >= 400) {
                        code.textContent = '✖ Error ' + xhr.status + ' while fetching file: ' + xhr.statusText;
                    }
                    else {
                        code.textContent = '✖ Error: File does n