The main before introducing the destructor

step3-main.c

int main()
{
    IntStack* stack = new_stack();
    for (int i = 5; i > 0; i--) {
        push_to_stack(stack, i);
    }
    printf("At the top of the stack is `%d`\n\n", peek_stack(stack));
    while (!is_empty_stack(stack)) {
        printf("`%d` was popped from the stack\n", pop_stack(stack));
    }
    free(stack); stack = NULL;
    return 0;
}