typedef struct {
unsigned long int reserved;
unsigned long int size;
void ( * copy_helper)(
void * dst,
void * src );
void ( * dispose_helper)(
void * src );
const char *signature;
} Block_Descriptor;
typedef struct {
void *isa;
int flags;
int reserved;
void ( * invoke )(
void *,
... );
Block_Descriptor *descriptor;
} Block_Literal;