docs: def visitLiteralRange(self, ctx: ShExDocParser.LiteralRangeContext):
          """ ShExC: literalRange: literal (STEM_MARK literalExclusion*)? 
              ShExJ: valueSetValue: objectValue | LiteralStem | LiteralStemRange
                     literalStem: {stem:STRING}
                     literalStemRange: {stem:STRING exclusions:[STRING|LiteralStem+]?
          """
          baseliteral = self.context.literal_to_ObjectLiteral(ctx.literal())
          if not ctx.STEM_MARK():
              vsvalue = baseliteral               # valueSetValue = objectValue / objectValue = ObjectLiteral
          else:
              if ctx.literalExclusion():          # valueSetValue = LiteralStemRange /
                  vsvalue = LiteralStemRange(baseliteral.value.val, exclusions=[])
                  self._literal_exclusions(vsvalue, ctx.literalExclusion())
              else:
                  vsvalue = LiteralStem(baseliteral.value)
          self.nodeconstraint.values.append(vsvalue)