@deftypefun {uint32_t *} {stringprep_ucs4_nfkc_normalize} (uint32_t * @var{str}, ssize_t @var{len})
@var{str}: a Unicode string.
@var{len}: length of @code{str} array, or -1 if @code{str} is nul-terminated.
Converts UCS4 string into UTF-8 and runs
@code{stringprep_utf8_nfkc_normalize()}.
@strong{Return value:} a newly allocated Unicode string, that is the NFKC
normalized form of @code{str}.
@end deftypefun