/* 
 * From the list pointed to by *user_ptr_del, delete the user 
 * with the given name. 
 * Remove the deleted user from any lists of friends. 
 * 
 * Return: 
 *   - 0 on success. 
 *   - 1 if a user with this name does not exist. 
 */  
int delete_user(const char *name, User **user_ptr_del) {  
    
      
}  