docs: def get_countries_in_region(cls, region, use_live=True, exception=None):
          # type: (Union[int,str], bool, Optional[ExceptionUpperBound]) -> List[str]
          """Get countries (ISO3 codes) in region
  
          Args:
              region (Union[int,str]): Three digit UNStats M49 region code or region name
              use_live (bool): Try to get use latest data from web rather than file in package. Defaults to True.
              exception (Optional[ExceptionUpperBound]): An exception to raise if region not found. Defaults to None.
  
          Returns:
              List(str): Sorted list of ISO3 country names
          """
          countriesdata = cls.countriesdata(use_live=use_live)
          if isinstance(region, int):
              regioncode = region
          else:
              regionupper = region.upper()
              regioncode = countriesdata['regionnames2codes'].get(regionupper)
  
          if regioncode is not None:
              return countriesdata['regioncodes2countries'][regioncode]
  
          if exception is not None:
              raise exception
          return list()