code: @Nullable
    public static String getDialCodeOfCountry (@Nullable final String sCountry)
    {
      if (StringHelper.hasNoText (sCountry))
        return null;
      return s_aCountryToDialCode.get (sCountry.toUpperCase (Locale.US));
    }
docs: Get the dial code for the specified country (in the ISO-3166 two letter
  type).
  
  @param sCountry
  The country code. Must be 2 characters long.
  @return <code>null</code> if no mapping exists.