code: def is_carrier_specific(numobj):
      
      region_codes = region_codes_for_country_code(numobj.country_code)
      region_code = _region_code_for_short_number_from_region_list(numobj, region_codes)
      national_number = national_significant_number(numobj)
      metadata = PhoneMetadata.short_metadata_for_region(region_code)
      return (metadata is not None and
              _matches_possible_number_and_national_number(national_number, metadata.carrier_specific))
docs: Given a valid short number, determines whether it is carrier-specific
      (however, nothing is implied about its validity).  Carrier-specific numbers
      may connect to a different end-point, or not connect at all, depending
      on the user's carrier. If it is important that the number is valid, then
      its validity must first be checked using is_valid_short_number or
      is_valid_short_number_for_region.
  
      Arguments:
      numobj -- the valid short number to check
  
      Returns whether the short number is carrier-specific, assuming the input
      was a valid short number.