Need help with the following methods, and please use C language, thanks!

/* Initialize the linked list to keep the history. */ List* init_history();

/* Add a history item to the end of the list. List* list - the linked list char* str - the string to store */ void add_history(List *list, char *str);

/* Retrieve the string stored in the node where Item->id == id. List* list - the linked list int id - the id of the Item to find */ char *get_history(List *list, int id);

/ *Print the entire contents of the list. */ void print_history(List *list);

/ *Free the history list and the strings it references. */ void free_history(List *list);