github.com/shohhei1126/hugo@v0.42.2-0.20180623210752-3d5928889ad7/tpl/tplimpl/embedded/templates/shortcodes/highlight.html

{{ if len .Params | eq 2 }}{{ highlight (trim .Inner "\n\r") (.Get 0) (.Get 1) }}{{ else }}{{ highlight (trim .Inner "\n\r") (.Get 0) "" }}{{ end }}