iceberg-theme/layouts/shortcodes/addtab.html (2 lines of code) (raw):

<input id="{{ .Get 2 }}" type="radio" name="{{ .Parent.Get 0 }}" onclick="selectExampleLanguage('{{ .Get 1 }}', '{{ .Get 2 }}')"> <label for="{{ .Get 2 }}">{{ .Get 0 }}</label>