text: /*See LICENSE file for copyright and license details.*/
  
  bool strcmp_sp(const char *s1, const char *s2);
  char *my_strdup(const char *s);
  void die(const char *errstr, ...);
  void *copy_to_heap(void *data, int size);
  
  Dir m2dir(V3i a, V3i b);
  V3i neib(V3i pos, Dir i);
  void fixnum(int min, int max, int *n);
  int rnd(int min, int max);
  
  #define COPY_TO_HEAP(data, type) \
    mk_node(copy_to_heap(data, sizeof(type)))
  
  bool is_able_to_inc_v3i(V3i *pos);
  void inc_v3i(V3i *pos);
  
  void *my_alloc(int count, int size);
  #define ALLOCATE(count, type) \
    my_alloc(count, sizeof(type))
  