{{- $section := default (.Get 0) (.Get "section") -}}
{{- if not $section }}
{{- errorf "missing parameter 'section': %s" .Position }}
{{- end }}
{{- $key := default (.Get 1) (.Get "key") -}}
{{- if not $key }}
{{- errorf "missing parameter 'key': %s" .Position }}
{{- end }}
{{- $page := index (default dict (index (default dict (index $.Page.Params "values")) $section)) $key }}
{{- $site := index (default dict (index $.Site.Data.values $section)) $key }}
{{- $value := default $site $page }}
{{- if not $value }}
{{- errorf "missing, empty or null value at 'values/%s.%s': %s" $section $key .Position }}
{{- end }}
{{- $value -}}