docs: def _language_exclusions(stem: LanguageStemRange,
                               exclusions: List[ShExDocParser.LanguageExclusionContext]) -> None:
          """ languageExclusion = '-' LANGTAG STEM_MARK?"""
          for excl in exclusions:
              excl_langtag = LANGTAG(excl.LANGTAG().getText()[1:])
              stem.exclusions.append(LanguageStem(excl_langtag) if excl.STEM_MARK() else excl_langtag)