hugo-theme-relearn/layouts/shortcodes/include.html

{{- $file := .Get "file" | default (.Get 0) }}
{{- $showFirstHeading := .Get "showfirstheading" | default (.Get 1) | default true }}
{{- if eq (printf "%T" $showFirstHeading) "string" }}
	{{- $showFirstHeading = (eq $showFirstHeading "true") }}
{{- end }}
{{- if not $showFirstHeading }}<div class="include hide-first-heading">{{ end }}

{{ $file | readFile | safeHTML }}

{{- if not $showFirstHeading }}</div>{{ end }}