Plan 9 from Bell Labs’s /usr/web/sources/plan9/sys/src/cmd/upas/bayes/msgdb.h
typedef struct Msgdb Msgdb; Msgdb *mdopen(char*, int); long mdget(Msgdb*, char*); void mdput(Msgdb*, char*, long); void mdenum(Msgdb*); int mdnext(Msgdb*, char**, long*); void mdclose(Msgdb*);