Ng_alert_notification .html is an incomplete template

I can’t find“ng_alert_notification.html”in“…/grafana/public/emails”, where can I download this file?
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I found the Ng_alert_notification .html file and put it in the folder, and then I sent the test email, it reports an error “failed to send test alert: html/template: ng_alert_notification .html is an incomplete template”
How can I address this issue?

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