User *find_user(const char *name, const User *head) {
    User *curr = (User *) head;
    while (curr != 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.