User *find_user(const char *name, const User *head) {
    // start at the first user object in the linked list
    User *current = head;
    // check if the name of every user is this name
    while(current->next != NULL){
        // if it is return a pointer to the user
        if (strcmp(current->name, name) == 0){
            return current;
        }
    }
    // if that never happens, return NULL
    return NULL;
}
