code: def country_code_for_valid_region(region_code):
      
      metadata = PhoneMetadata.metadata_for_region(region_code.upper(), None)
      if metadata is None:
          raise Exception("Invalid region code %s" % region_code)
      return metadata.country_code
docs: Returns the country calling code for a specific region.
  
      For example, this would be 1 for the United States, and 64 for New
      Zealand.  Assumes the region is already valid.
  
      Arguments:
      region_code -- The region that we want to get the country calling code for.
  
      Returns the country calling code for the region denoted by region_code.