Hi, I have the following piece of code that is generating the above assertion. Could someone tell me what is going wrong: template <typename T> struct my_node_t : public avl_set_base_hook<> {   my_node_t(T data): m_data(data) {}   template <typename U>   friend  bool operator< (const my_node_t<U>& lhs, const my_node_t<U>& rhs) {       return lhs.m_data < rhs.m_data;   };   T m_data; }; typedef my_node_t<int> avlnode_t; typedef avltree<avlnode_t> avltree_t; struct args_t {   unsigned int seed[MAX_THREADS];   vector<avlnode_t>* items;   avltree_t* tree_ptr;   thread_args_t(size_t num_threads,                 avltree_t* map,                 vector<avlnode_t>* init_vec,                 size_t num_entries,                 unsigned int s)  {     num_items = num_entries;     tree_ptr = map;     initial_items = init_vec;     for (size_t i = 0; i < num_threads; ++i) {       seed[i] = i + s;     }     for (int i = 0; i < 10; ++i) {       initial_items->push_back(i * 100);     }     for (vector<avlnode_t>::iterator it = initial_items->begin(); it != initial_items->end(); ++it) {       tree_ptr->insert_equal(*it);     }   }   ~thread_args_t() {     tree_ptr->clear();     delete tree_ptr;     delete initial_items;   } }; void worker(void* args_ptr) {   args_t* args = static_cast<args_t*>(args_ptr);   avltree_t* tree = args->tree_ptr;   vector<avlnode_t>* values = args->initial_items;   int index = 5; //generate_random<int>(my_seed, 0, num_items + 1)))   avlnode_t& find_element = *(values->begin() + index);   tree->insert_equal(find_element);   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ <-raises exception } int main() {   int num_threads = 1, num_entries = 10;   vector<avlnode_t>* init_vec = new vector<avlnode_t>;   avltree_t* tree = new avltree_t;   args_t* args = new args_t(num_threads, tree, init_vec, num_entries);