bin_tree.c :

/* a_bin_tree_height(a) : returns the maximum height of the binary tree a.
Returns 0 if a is NULL.
*/
int a_bin_tree_height(a_bin_tree * a);

/* a_bin_tree_maplevel(a, l, f) : apply f to all the nodes of the binary tree a at the level l.
The root of a is at level 1.
Modify a in place.
Do nothing if a is NULL.
*/
void a_bin_tree_maplevel(a_bin_tree * a, int level, int (*f) (int));

/*
a_bin_tree_map_bfs(a, f) : apply f to all the nodes of the binary tree a with a breath-first traversal.
Modify a in place.
Do nothing if a is NULL.
*/
void a_bin_tree_map_bfs(a_bin_tree * a, int (*f) (int));