make_file_from_tree(search_tree* head, char* filename)
{
    FILE *out = fopen(filename, "w");
    if(out == NULL){
        perror("make_file_from_tree: Can`t open output file.");
    }else{
        void print_tree_node(FILE* output, search_tree* cur)
        {
            fprintf(f, "%s: %d\n", cur->key, cur->value)
        }
        visit_recursive(head, print_tree_node);
    }
}