extern void *afb_context_make(struct afb_context *context, int replace, void *(*make_value)(void *closure), void (*free_value)(void *item), void *closure);
extern void afb_context_close(struct afb_context *context);
extern void *afb_context_make(struct afb_context *context, int replace, void *(*make_value)(void *closure), void (*free_value)(void *item), void *closure);
extern void afb_context_close(struct afb_context *context);