code: def _region_code_for_short_number_from_region_list(numobj, region_codes):
      
      if len(region_codes) == 0:
          return None
      elif len(region_codes) == 1:
          return region_codes[0]
      national_number = national_significant_number(numobj)
      for region_code in region_codes:
          metadata = PhoneMetadata.short_metadata_for_region(region_code)
          if metadata is not None and _matches_possible_number_and_national_number(national_number, metadata.short_code):
              # The number is valid for this region.
              return region_code
      return None
docs: Helper method to get the region code for a given phone number, from a list of possible region
      codes. If the list contains more than one region, the first region for which the number is
      valid is returned.