extern void *afb_context_get(struct afb_context *context);
extern void afb_context_set(struct afb_context *context, void *value, void (*free_value)(void*));
extern void *afb_context_get(struct afb_context *context);
extern void afb_context_set(struct afb_context *context, void *value, void (*free_value)(void*));