#define dl_next(p) *((void**)&(((struct __dl_head*)(p))[-1].dh_next))
#define dl_prev(p) *((void**)&(((struct __dl_head*)(p))[-1].dh_prev))
-void *dl_head();
+void *dl_head(void);
char *dl_strdup(char *);
char *dl_strndup(char *, int);
void dl_insert(void*, void*);