/* a_bin_tree_is_search_tree(a) : returns 1 if a is a binary search tree, otherwise returns 0 */
int a_bin_tree_is_search_tree(a_bin_tree * a);

/* a_bin_tree_contains(a,x) : returns 1 if x belongs to the values of the nodes in a, otherwise
returns 0. */
int a_bin_tree_contains(a_bin_tree * a, int x);
nothing