{{- $subdir := strings.TrimSuffix (relLangURL "/") (relLangURL "") }}
{{- $url := .RelPermalink }}
{{- $url = replaceRE "/[^/]*$" "" $url }}
{{- $rel_url := strings.TrimPrefix $subdir $url }}
{{- $rel_url = replaceRE "/[^/]*" "/.." $rel_url }}
{{- $rel_url = trim $rel_url "/" }}
{{- return $rel_url }}