+link_t* list_insert(link_t* head, unsigned index, int value) {
+
+ if (index == 0) {
+ return list_prepend(head, value);
+ } else if (index == list_count(head)) {
+ return list_append(head, value);
+ } else {
+ link_t* link_insrt = list_new(value);
+ link_t* head_first = head;
+ link_t* head_next = NULL;
+ for (unsigned i = 0; i < index-1; i++) {
+ head = head->next;
+ }
+ head_next = head->next;
+ head->next = link_insrt;
+ head = link_insrt;
+ head->next = head_next;
+ return head_first;
+ }
+}
+
+link_t* list_delete(link_t* head, unsigned index) {
+ link_t* head_prev = NULL;
+ link_t* head_next = NULL;
+ link_t* head_ret = NULL;
+
+ if (head == NULL) {
+ return NULL;
+ } else if (index == 0) {
+ head_next = head->next;
+ free(head);
+ head = head_next;
+ head_ret = head;
+ } else {
+ link_t* head_first = head;
+ for (unsigned i = 0; i < index-1; i++) {
+ head = head->next;
+ }
+ head_prev = head;
+ head = head->next;
+ head_next = head->next;
+ free(head);
+ head = head_prev;
+ head->next = head_next;
+ head_ret = head_first;
+ }
+ if (head_ret != NULL) {
+ return head_ret;
+ } else {
+ return NULL;
+ }
+}
+
+link_t* list_concat(link_t* first, link_t* second) {
+ link_t* head_first = first;
+
+ while (first->next != NULL) {
+ first = first->next;
+ }
+ first->next = second;
+ return head_first;
+}
+
+link_t* list_sort(link_t* head) {
+ int tmp;
+ bool isswaped;
+ link_t* head_first = head;
+
+ do {
+ isswaped = false;
+ while (head->next != NULL) {
+ if (head->value > head->next->value) {
+ tmp = head->value;
+ head->value = head->next->value;
+ head->next->value = tmp;
+ isswaped = true;
+ }
+ head = head->next;
+ }
+ /* Reloop at the beginning of the list until there's is values swaped */
+ head = head_first;
+ } while (isswaped);
+ return head_first;
+}
+