Converts the argument, a wide-character code, to lowercase.
    If the argument is not an uppercase character, it is returned
    unchanged.

    Format

      #include  <wctype.h> (ISO C)

      #include  <wchar.h> (XPG4)

      int towlower  (wint_t wc);

1 - Argument

 wc

    An object of type wint_t representable as a valid wide character
    in the current locale, or the value of WEOF. For any other value,
    the behavior is undefined.

2 - Description

    If the argument is an uppercase wide character, the corresponding
    lowercase wide character (as defined in the LC_CTYPE category of
    the locale) is returned, if it exists. If it does not exist, the
    function returns the input argument unchanged.