ALLEGRO_USTR - Allegro 5 API

       An opaque type representing a string.  ALLEGRO_USTRs normally contain UTF-8 encoded strings, but they may
       be used to hold any byte sequences, including NULs.

Allegro reference manual                                                                   ALLEGRO_USTR(3alleg5)

       ALLEGRO_USTR - Allegro 5 API

              #include <allegro5/allegro.h>

              typedef struct _al_tagbstring ALLEGRO_USTR;