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`iswalnum'--alpha-numeric wide-character test

     #include <wctype.h>
     int iswalnum(wint_t C);
`iswalnum' is a function which classifies wide-character values that
are alpha-numeric.
`iswalnum' returns non-zero if C is a alpha-numeric wide-character.
`iswalnum' is C99.
   No supporting OS subroutines are required.