What does this Go snippet output?

1package main
2 
3import "fmt"
4 
5type S struct{ data []int }
6 
7func (s S) Sum() int {
8	t := 0
9	for _, v := range s.data {
10		t += v
11	}
12	return t
13}
14 
15func main() {
16	s := S{data: []int{1, 2}}
17	defer fmt.Println(s.Sum())
18	s.data = append(s.data, 100)
19	fmt.Println("appended")
20}