Rust: How do you implement FromIterator?

1let numbers: Vec<i32> = (1..=5).collect();
2let sum: i32 = (1..=5).sum();
3let doubled: Vec<i32> = (1..=5).map(|x| x * 2).collect();

1struct Stats {
2    sum: i32,
3    count: usize,
4}
5
6impl FromIterator<i32> for Stats {
7    fn from_iter<I: IntoIterator<Item = i32>>(iter: I) -> Self {
8        let mut sum = 0;
9        let mut count = 0;
10        for val in iter {
11            sum += val;
12            count += 1;
13        }
14        Stats { sum, count }
15    }
16}
17
18let stats: Stats = (1..=10).collect();