inline int llist_add(linked_list *list, void *obj);
inline void llist_remove(linked_list *list, int idx);
inline void llist_travse(linked_list *list, void (*)(void *));
inline void llist_deep_travse(linked_list *list, void (*)(void *));
inline int llist_find(linked_list *list, void *obj);
inline void *llist_shift(linked_list *list);
inline size_t llist_len(linked_list *list);

struct item_st {
  _Bool is_list;
  union {
    linked_list *ls;
    size_t ptr;
  };
}

typedef struct lnode_st {
  void *self; lnode_st *sub; lnode_st *next;
} lnode;

nodea {
  a
  b
  c {
   d {
   }
  }
}

node b {

}

c
d
e

self: duangsuse\0
sub:
  self: bird\0
  sub:
    self: flower\0
    sub: NULL
    next:
      self: butterfly\0
      sub: NULL
      next: NULL
  next: NULL

duangsuse {
  ...
}

self: duangsuse
sub: ...
next: NULL

bird {
  flower,
  butterfly
},
{},
dog,
dolphin

self: bird
sub:
  self: flower
  next:
    self: butterfly
next:
  next:
    self: dog
    next:
      self: dolphin

data class LinkedList(Int size, ListItem head, ListItem tail)
data class ListItem(ListItem next)
data class ListObjectWithSublist(Object ptr, LinkedList sub): ListItem
data class ListObject(Object ptr): ListItem

[self] {
  [item],
  [item2]
},
[item]