code: def _prefix_number_with_country_calling_code(country_code, num_format, formatted_number):
      
      if num_format == PhoneNumberFormat.E164:
          return _PLUS_SIGN + unicod(country_code) + formatted_number
      elif num_format == PhoneNumberFormat.INTERNATIONAL:
          return _PLUS_SIGN + unicod(country_code) + U_SPACE + formatted_number
      elif num_format == PhoneNumberFormat.RFC3966:
          return _RFC3966_PREFIX + _PLUS_SIGN + unicod(country_code) + U_DASH + formatted_number
      else:
          return formatted_number
docs: A helper function that is used by format_number and format_by_pattern.