blog.grink.tech/custom-theme/templates/include/gtm.html

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    w[l].push({ 'gtm.start': new Date().getTime(), event: 'gtm.js' });
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        j = d.createElement(s),
        dl = l != 'dataLayer' ? '&l=' + l : '';
    j.async = true;
    j.src = 'https://www.googletagmanager.com/gtm.js?id=' + i + dl;
    f.parentNode.insertBefore(j, f);
})(window, document, 'script', 'dataLayer', '{{ GOOGLE_TAG_MANAGER }}');
</script>