code: @Nullable
    public static String unifyIBAN (@Nullable final String sIBAN)
    {
      if (sIBAN == null)
        return null;
  
      // to uppercase
      String sRealIBAN = sIBAN.toUpperCase (Locale.US);
  
      // kick all non-IBAN chars
      sRealIBAN = RegExHelper.stringReplacePattern ("[^0-9A-Z]", sRealIBAN, "");
      if (sRealIBAN.length () < 4)
        return null;
  
      return sRealIBAN;
    }
docs: Make an IBAN that can be parsed. It is converted to upper case and all
  non-alphanumeric characters are removed.
  
  @param sIBAN
  The IBAN to be unified.
  @return The unified string or <code>null</code> if this is no IBAN at all.