typedef struct COS_Cons_ent COS_Cons_ent;
typedef struct COS_Cons_ent* COS_Cons;
COS_Cons cos_cons (COS_object car, COS_object cdr);
typedef struct COS_Cons_ent COS_Cons_ent;
typedef struct COS_Cons_ent* COS_Cons;
COS_Cons cos_cons (COS_object car, COS_object cdr);