User *find_user(const char *name, const User *head) {
    User curr = *head;
    while (curr.next != NULL) {
        if(strcmp(curr.name, name) == 0) {
            return &curr;
        }
        curr = *curr.next;
    }
    return NULL;
}
Return a pointer to the user with this name in the list starting with head. Return NULL if no such user exists.
 NOTE: You'll likely need to cast a (const User *) to a (User *) to satisfy the prototype without warnings.